Whether you're spectating a game or playing a different champion, what certain behaviors and mechanics do you witness that you feel contributes negatively to your main champion? Comment! *Please keep the topic on the champion's mechanics instead of common player knowledge.
buying 
without the skill to properly last hit. Do it like me and buy coin ffs.
leading with a bubble toss.
Seriously... use your E to slow them down first... It's so much easier to hit a slow target.
So, I have no specific main, I just have my holy trinity.
Starting with 
;
-If they go aggressive early against these specific champions: Darius, Lulu, Fiora, Lissandra, Ryze, Gnar, Kayle, Kennen, and of course, the biggest, Vayne. (I hate any of you people that bring Vayne top. :p)
-If they build a large amount of mana. Though his passive makes it look like you want mana, there are better choices. Late-game, if you're managing your abilities properly, you won't run out of mana. Also, if they leave Q(Poison trail) on, or off.
-If Rylai's doesn't end up in their build.
-If Rylai's isn't an early pickup, either a rush item, or the second option.
-If they build Tear. Like, at all. Just don't. It's not good on him. RoA is a better option if you want a scaling item. Tear takes too long to build up and forces you to focus on it rather than build the proper, powerful items on him(Deadman's, Rylai's, Banshee's, or Spirit Visage).
-If they don't know what to build. I forgive and feel bad for any new Singed players, as there is so much shit that works on him, it can be pretty jarring.
-If they aren't spamming laugh/taunt/joke any chance they get. THIS IS THE MOST IMPORTANT.
-The one above is a lie, if they don't animation cancel said emote spam while running, it is the clearest signal that they are new to Singed,
Next is 
;
-The biggest, I think, out of all of them: Their cs score. Swain is difficult to last hit with.
-If they leave their ult on for more than six seconds at a time. (If they do this, they're not effectively managing their mana.)
-If they start W. Alternatively, if they max anything else first that isn't his E. How you should almost always prioritize with maxing is E > Q > W, it should go without saying that you put a point in your ult whenever possible.
-If they go Thunderlords. Deathfire is the most effective Keystone for him in my eyes. I've garnered more success with it in my matches than Thunderlords.
-If they don't rush either Zhonya's or Rod of Ages. Both of which are extremely useful on him.
-If they go tear, or cooldown reduction items. Exceptions of this are Spirit Visage, and Will of the Ancients. Less so for Will of the Ancients, due to how it works now passive-wise. There are better options, but if the situation demands a WotA, get a WotA. This said situation is where you can get abilities off on enemies, but they can easily whittle you down even in ult form. I good case of this is if they build Grievous specifically to counter your ult. As long as you have dots burning on them, you'll be regenerating hp, albeit slowly.
Last is 
;
-If they don't Man drop gank.
-If they don't Q before W'ing on someone for the combo. Alternatively, if they don't throw a cheeky spear after the combo is finished.
-If they aren't using his E passive to cs. Like, seriously. It's difficult to not get cs on him, as the kill is almost guaranteed on any minion. Plus, you can use Q to farm any minions that are too far away to jab, as his E passive applies to his Spear toss as well.
playing so passively
not maxing charm second. (last night i play a game where i didn't max charm second for the first time in a while regretted it.)
EVERYTHING YOUR DOING IS WRONG STOP SPAMMING W FOR NO REASON(A good jhin player learns not to spam w when w is the most important thing in your kit on a 10 second cool down.)
everyone that tries to play her in free week. I see these games as free wins. 1 out 10 games during free week I found that there is one decent among those who try. Because I know there people say elise takes no skill but she actually does. Just look at free week.
spams decoy till he runs out of mana. Seriously, that is your best and sometimes only means of escape, spamming it is a sure fire way to make yourself a sitting duck.
On the other hand, I know people are playing him well when they have his "fake decoy" down pat.
Any Jungler: Buying Refillable potion.
I look at there build and they way they attack champions. There character placement in lane.
Whenever a Yorick skips getting mana items
When your 1st 2 items on Malz are tear and Ludens. They always lose lane and whenever an ally is playing Malz they use this build. Wanna rip my hair out
You can tell a bad Thresh from level 1, exhaust, blood moon, starts q, rushes face, maxes q, never flays, never lanterns, and never ults
Oh and also coin
When they take windspeakers.
When they land their ult and then miss the followup Q.
When they fail to CC an enemy who took a magical journey.
When they take standard AP runes.
When they completely abandon botlane.
using R to directly gank, starting q on lvl 1, not reseting autoattacks with e,building her devourer,and ofc building wrong items on her
Using an AD blue build as mid against an AP team as the only source of AP damage outside of the tanky support in his own team.
"Oh boy another Kha player!"
Starts 
x3
"uh, where's your refillable dude?"
"Can't clear without 3 reds."
Meanwhile any competent Kha player can manage with refillable leashless if they, you know A) Smite properly B) Kite & Cancel animations properly C) Do Skuttle
The three red potion start to me is a sign that they can't work around Kha's weaknesses.
maxing W second or using ult with 1 or no balls thinking it would do dmg.
Sion: Trying too hard to hit a fully charged Q. Focusing kills rather than CS or objectives in his passive. Complaining that his shield can't do shit despite only having one rank in it and the rest in the unreliable Q.
Fiora: (Not a Fiora main) using the riposte to slow people instead of blocking and not following up. Thanks for telling people your defensive option is on cooldown.
It's pretty obvious if an Irelia player doesn't know the champions' powerspike.
So it depends on matchups. Like fighting Renekton too early, or fighting Jax too late.
Also not making use of the Q reset mechanic when going for the kill is a common indicator of an inexperienced Irelia player. ICU calls this "Irelias sticky Q" <video>. It's one of the more easily understood mechanics but can be difficult to use in the heat of the moment.
All sorts of ways.
Failure to use the toggle off tick of R to last hit minions. Failure to E>R when possible, rather than R>E. Weird/ improper use of W Low/ infrequent use of W Failure to interrupt critical channels with W (e.g. Katarina R) Using QQE rather than QEQ where possible. Using Q at easily avoidable times. Not abusing FoW to try to land Q. Failure to combo Q with W and or R. Poor use of auto attack range, especially early. Buying Morello, ever. Buying Tear in bad early matchups (e.g. vs Fizz) Taking Barrier, Heal, or Ghost. Playing Passive with Egg or Aggressive without Egg. Building Void Staff late Building Zhonyas in the wrong matchups
There are oh-so-many more.
:
-When they use their W to either go after minions or attack a champ. You want to waveclear minions while poking down the champ.
-Taking on multiple opponents at once; Talon is a champion where you focus your combos on one champion at a time
-Not poking their enemies down; going in against a full health champion is something you do with late-game uber snowball Talon with lifesteal
-Using his ult only as an escape tool or going in; his ult has SO many possibilities: escape tool, opening, chasing, burst, etc.
-Buying 
. I don't see how that really helps, use 
instead.
-When they do use , not using it's active against champions. Seriously. Use it against champions. It works.
-Using 
and 
instead of 
and 
. Definitely use Flash and Ignite.
Kog'maws building guinsoo's first.
You need attack speed to stack it with any sort of speed first T.T Otherwise by the time it hits 8 stacks they are either dead or you are!
When they play really passive and never auto the enemy laner when their Mantra is on CD.
Not knowing when to back out for a moment to grab the blobs or when to stay in the thick of the fight. On that note, just not understanding the blob mechanic in general; missing out on loads of healing, or abandoning your teammates to grab health you don't really need.
Not leading the slingshot. Not understanding how strong hitting multiple targets is; you spawn a blob per target hit.
Only using ult if the first bounce will hit several people; you get 4 chances.
Not realizing how much hp your abilities cost later on, if you use full combo at full hp, you're spending 12% of your max. There is no "full hp engage" on Zac.
Brings on 
Rush 
on 
(Upgrading anything other then E first for his first evolution)
No management on 
Heat
Quickly kill the front 3 melee minions, and get the 3 casters to a little under half health, then Q one for the bounce for super damage/harrass on the lane opponent. I hate seeing people just spam Q for wave clear.
- misusing her ultimate.
I spot loads of free kills when my allied Jinx has her ultimate off of cooldown and she doesn't take them.
It's not so bad when she uses it for a non-kill, as sometimes the damage pressure is necessary or she's thinking something different. Missing free kills though is really frustrating. Especially the insanely easy ones.
Leblanc missing chains and tryndamere wasting/not using his ultimate
Kog'Maws who don't build rageblade first.
When they build Defense..............
when they take deathfire, no the passive works well with thunderlords.
When they don't use e+q combo... This is such a powerful harassing tool and some people don't use it enough. Also, when people build full AP support lulu. I don't think that lulu support should be used like lux support.
