I'd probably have to say a "yes" has to be somewhere in there for me. If I have no reason not to believe someone, I'll believe him or her. But I'm gullible, I admit. Though not completely naive or anything. I f that makes sense.
Not ALL the time but never trust a drug addict and their clever scams. Guy I somewhat knew came to me said there was a job for two of us to work the next day. I agreed to work with him next day so uh.. could I lend him $20 till we get paid? Sure -but next day no job existed and he made 'excuse' why the work disappeared. Course I never got my $20. neither.
Not professionally, but personally, yes sometimes. I give people the benefit of the doubt a little too often, but I prefer that to not ever trusting anyone.