I've never worked for them, thankfully, but I have never found anything trustworthy about Manpower, Inc.
They creeped me out, too. I used to work for them between military assignments when I was in the ARNG, on and off of Active Duty. I lasted for three assignments, and $8 an hour wasn't enough to waste my time each day.
One day I was put in an office to answer the phone for some Big Wig at a Big Insurance Company. It rang ONCE all day...and it was a wrong number, LOL!
I did get to read his Wall Street Journal that day, so it wasn't a total loss. ;)