If I'm remembering right, the transporter accident that made Tom Riker was because atmospheric conditions were hella crazy - he wasn't really evil, just spent far too long on his own (Riker all alone on an entire planet, how did he survive?
). Evil bearded Kirk came from an alternate dimension (the one kinky Kira is from). There was a time when Kirk (and that little dog) was split into a good (timid) one and an evil (aggressive) one, but that had something to do with yellow powder (or was it a plant?). That's all I can remember
That won't save you. You'd have to lock your wardrobes also.