But, but, I hate them and they're unworthy of my trust.
your instincts are probably right!

It is a very subtle thing, and I don't think many people are good at it, at least judging from how awkward and flustered most people seem when caught in these situations. Case in point, rdgrad's wallet thief lady. She handled that situation terribly and turned a small kindness into something painfully awkward for everyone involved.

I would've fought her for taking my wallet. Seriously.