I'm honestly guilty of just snapping at people when they perform poorly. I have my games too so I try my best to remember that I also do badly. However, some times it just IRKS me when someone does something so obliviously bad and then spam a missing ping on a teammate or something. I just snap at that point.
If you're new to the game, I'd honestly need you to let me know before I treat you any differently. There aren't really much new players I run into, so if I do, then it's legit almost impossible for me to tell. So if I badmouthed and you say, "Well, I'm new. Instead of flaming me, why not give me advice?", I'll have to swallow my pride, apologize and then I can help you out from there.
I've actually given a lot of people on the enemy team advice. They tend to take it to heart, especially when you've already won lane vs them. I like helping people improve and helping them out along the way. I also like when people give me advice. I'm not the best, so you give me advice, I'll take it to mind. Likewise, if someone is outperforming you, it'd be wise to take their advice.
And, as usual, I can spectate and help out people for free if they want a bit of advice. :) Most of it is just hand me down information that I got from higher elo people helping me out, but I don't mind returning the favor.