I feel all my current colleagues are trustworthy - we need to be a good, cohesive team because we look after vulnerable people - but I have had colleagues I definitely didn’t trust before. Ironically I talked, and occasionally socialised with them more than I do with my “better” colleagues, but I had a different role back then. Now, I work by myself and mostly talk to others in passing.
I do think keeping to your personal boundaries around colleagues is a good idea. It sucks but sometimes getting too involved isn’t worth the drama.