I'm also all for pet sitting services, then again I am a pet sitter. But when I do a job I make sure that I do everything I am asked to and because I love animals so much most of the time I end up staying at a clients house even longer then they paid for just because I'm having a good time playing with the animals.
But I understand what it's like to have a friend do a bad job I had my roommate take care of my cats once and she didn't scoop out the litter box and Corkscrew poops on my bathroom floor when the litter isn't clean. And she also didn't give them and canned food, I was so upset. And it's a horrible thing to come home to from a vacation.