Is there any way to check a person's past "sitters"?

Is there a way to check what past reviews the pet owner has given? Like how Amazon lets you see what reviews people have left.

I'm having so much trouble with a cat I am taking care of and he says it is odd because he hired a sitter a month ago, but I don't think the cat had been diagnosed with diabetes a month ago. I just want to know if there is any way to speak to this sitter because I feel that he is not giving me the right information since his cat is so aggressive and he was not able to book the sitter again. Please let me know!

Also, any advice on how to get a cat to trust you? Dogs are so much easier!