The only multiplayers I have got into were populated by people I could chat to decent players playing for a long time. Very little abuse, trolls tended to get picked on, see below.
One TPS had various character skins, often the females were chosen due to nicer bums to look at, but some sexist players blocked you in corners and taunted (so you grenade suicided), those idiots got hounded off, just to say grenade team kills are usefull.
I also remember uploading game play glitches to the dev team, and for fun I patrolled one glitch and killed the glitcher EVERYTIME they went for it.
A FPS I played a lot also had glitchers but they were shootable, put yourself somewhere safe and pick them off as they tried to climb off the map.