Personally, I would never hire a pet sitter just because I am paranoid about people being in my house when I'm not around. I won't let anyone in my home if I can't monitor them. If it's someone I know really, really well (i.e. a relative) then I may make an exception. Otherwise, there's no chance. I won't let a very close friend come over if I'm not there. I'm very weird that way I know. That's the main reason why I would board.