As a tank a few things
If multiple people start getting super toxic and calling me a retard for wahtever I will leave. I don't mind being called out for mistakes especially if they clearly explain how I could have done butter, but people who are just straight up namecalling and being abusive isn't something I put up with.
If the DPS/Healer are vastly undergeared/underskilled and it looks like over an hour dungeon run I will leave