Erm I'm not happy of what I did when I was a low level but here are the things:
Scamming for rare items,
Booting people randomly,
Cussing (this was minor),
Begging,
spamming sales,
I do this these days:
When some low level needs help I just abandon them in a game,
Leaving when someone asks me a question.
I could go on forever honoestly....