Guess i'm an optimist and think that the majority of people are good, however i still have locks on everything! Also, forget service people, how about your friends, or kids friends. My parents always told me "don't bring your friends in the house or show them your valuables, they will steal them". I always thought they were paranoid and of course "none of my friends ever stole anything", or at least until I saw a "friend" steal something at another friends house. That is crazy and gives you the worst knots in your stomach, not to mention you lose your trust of EVERYONE!
When I was a kid, several of the neighbors got robbed, it turned out some neighborhood kids were telling mommy and daddy what everyone else on the block had at their house! The parents were running a little theft ring, and this wasn't in some scumbag neighborhood either, I would consider my family as upper-middle class. I don't recall the specifics about the bust, because I was a kid, but I do recall it was shear accident that they were busted.
Of course I tell my kids the same, however they don't have a clue. So, i lock everything up.
Cheers,
Tim