I love helping people! I've never been able to tell if someone just doesn't know what my champion does, but I've had people make unintelligent decisions against me. For example, I was playing Karthus, and the opposing Lux was having difficulty dodging Lay Waste. I go for an all in, and she doesn't back off despite being slightly lower than I. I take her down in a close trade with sustained damage.
I tell her, "Close one Lux! Next time, don't let me get so close. Abuse your range". I don't tell her to dodge my skillshots beforehand because that's something she knows to do already; she's just bad at it. She said nothing, but she took in the advice, for she stood further back and took much less harass from me.
Another time I was playing Shyvana top against a Yasuo. He was Summoner level 18, but his cs was very good and he played the champion pretty well, so at first I thought he might be a silver smurf or something. He didn't trade well though, and he let me get auto attacks off on him and chase him off of the minion wave. He also pushed hard and opened himself up for ganks. I decided that he was in fact a level 18 Summoner, and that while his mechanics were all right, he didn't have good knowledge of the game. So I started teaching him. "Hey Yasuo, your cs is really good. you're pushing too far though." "That opens you up to ganks." "Also don't let me attack you without attacking me back" "also just don't let me run up to you in the first place" "you have longer range than me so you can harass and back off when I run at you". I spent about twenty seconds at tower typing this, gradually forgoing grammar conventions because I was losing minions at tower, but I still soaked up exp, and I definitely think I helped the guy. He did not act angrily at me for giving him advice. He thanked me. Later when I told him that he was doing a great job keeping his creep score up but still needed to play safer because Lee Sin saw him as an easy lane to gank, one of the other opponents, Nocturne, spoke up, "youre too nice shyvana. i cant gank you". This was in spite of me being an autopushing champion at Yasuo's tower most of the time. (I still felt like I had an obligation to my team to try my best. Not playing at my best would also deprive Yasuo of his learning experience.) The Anivia support then said, "Thanks for teaching our new friend, we really appreciate it". As the game transitioned to middle game and I started being more directly involved in my team they started targeting me, but that was just because they wanted to win as much as we did.
I had a good time in both games, and I'm glad I was able to make some people's days better.