Hiya.
A friend of mine named Dave (he died a couple years ago; great guy) was playing a kender-like character (I believe he was a halfling named Teeble) once when I was a player. He stole something from my characters pack...iron spike, jar of honey, something like that. Anyway, there was some point in the adventure where we were all gonna be hurting bad if we didn't do something quick. I told the DM I "Get the [item] out of my pack and cram it in the hole before it erupts in flame again!" (or something like that; this was 20'ish years ago)...."You don't have [item]". Short version, we look at the 'kender' and say, "Well? You have it, you do it". The look on Daves face when he realized that his character might actually
die because of his kleptomania was absolutely
priceless! We all sat there, perfectly willing to let all our characters die, including his. The backpedaling and word-sputters uttering forth from the kender-player's mouth was quite delicious! In the end, he made the dice rolls and stopped the trap, IIRC. Of course, this only spurred on delusions of grandure on Teebles part...but it was still worth it.
Sorry for the mini-diversion there...
As for evil PC in non-evil group. I let players use "player gut feelings" with a wide berth in this regard. I mean, if an NPC joins the group, and suddenly money, gems etc. start disappearing, or start appearing in the NPC's pouches after a successful dungeon delve...players will put two and two together REAL fast. Evil NPC's just wouldn't last long in the group after that; extra watching, sneaky spell casting, detecting evil, baiting, etc. As soon as the NPC "gets caught" doing that





...roll initiative. So...evil-PC's who try and pull that stuff get the same treatment as an evil-NPC who did. It usually ends in the evil-PC's player rolling 3d6, in order (call it Karma...

).
^_^
Paul L. Ming