The problem is to find common guidelines for removal.
Every case is more or less uniqe and admins need to look into each and every single one of them before making a fair decision.
This will always be a problem imo. the best way is to report everytime, if you think a player is not suitable for XP check the forums for a tread and speak your mind to let admins know what you think.
I totally agree on that.
A common guideline doesn't seems to be possible. But, through some stuff happening in specific games, we can have nice informations, like not going bkb vs mass stunners, having sf or potm or such heroes vs warlock/omni and not going diffusal, no dagger on tide/enigma etc etc
Everygame has a special context, but still, some valuable informatiosn can be gathered and then decicion can be made.