I have serious trust issues as it is. I also REALLY value my privacy (my blinds are almost always closed in my home). All of the doors to my home stay locked at all times (unless someone is going through the door; otherwise, it's locked).
When I originally moved into this home back in '95, one of the movers stopped just outside of the truck, looked around the neighborhood and said: "You know, we never usually come up to this neighborhood - unless we're gonna steal something". Maybe he was joking, maybe he wasn't. Whatever the case, the guy was getting a good look at everything I owned. Luckily, I was just an E5 in the USAF with 2 young kids and didn't really own anything of value back then. The house was the most I could afford on my salary and that's where all of my $$ was going!
Staying out of their homes saves you from 2 possible bad scenarios:
(1) Your getting mugged
(2) Later facing an accusation that YOU stole something while in their home.
Sure, most all service workers are legit and just want to do their job without any trouble. But, do you want to take the chance that you've got the thieves of the lot in your home?
I keep an exceptionally close eye on them when they have to come into my home. I remove as much as possible that I own from their sight before they come in. I take them on the most direct route to what they've got to work on. Once they leave, I double check things like window locks, etc. Particularly in the bathroom.