Anyone who considers himself evil might group with a goodie for a variety with reasons, but I cannot see a single real reason for a goodie to group with an evil and still remain in the "good" area.

If you're willing to offer assistance someone you know has killed orphans/elves/everyone else because you both have similar interests, that is not an inherently good action, that is an inherently neutral or possibly evil action.

"For the sake of convenience I'll fight alongside you even though I was friends with that storm giant whose ribcage you're wearing and I knew the babies whose skulls hang from your flail."

Um, yeah, you must play some really screwed up goodies, then. He has a red aura for a reason: its not cause he walks old ladies across busy streets. Its cause he steals their purses afterwards and beats them for fun.