We had one person we hired as a contractor, but then her voice changed on the phone, and started calling people by their last names in chat. It looked like it was someone that subcontracted another who then quit, and the first was trying to hold onto the contract as long as possible.
Another answered complex questions during the interview, but after the start they knew nothing.
A third contractor I knew was trying to do two jobs at the same time. Unfortunately while he was supposed to be working for one company he was making public github commits for the second. He was shown the door that day.
Tangentially, another contractor "lost" two macbooks assigned to him. Apparently right after travelling to Colorado after they legalized weed.