here's some:
relax! it's in your head. (and apparently in a lot of heads on this thread!) that's how paranoia works = from the inside out.
i play with adults, so: not only would i enjoy hearing the input of others, i'd also feel rude (self-conscious) not inviting another bass player to check out my 'stuff' --- my ax, my rig, my ideas, yada yada. i'd be more interested in his/her thoughts about how to make the music better (it doesn't mean that i'd agree...but i'd be interested!).
i'm with the group who doesn't feel threatened by this situation. OP: good luck with your trust issues!