@boomerang,
boomerang, I had a very similar dilemma a few years ago, when my then partner & I were heading off to Asia for 3 months travel. A friend of a friend was staying at our house for the duration & offered to look after our 3 cats. She was very persuasive, said it would be a pleasure (as she really liked cats) & no trouble at all ... I couldn't quite put my finger on why, but I felt quite apprehensive about the idea & we ended up boarding the cats instead. On our return we discovered that she actually hadn't been at the house all that much, had neglected to pay a few bills (We weren't charging her any rent. The deal was she just paid for any bills she incurred, nothing else ...) & our friend had to come over & help her clean up the house before our return because she was having difficulty coping with other problems in her life .....
I'm really glad we didn't leave our precious critters in her care for so long, though I would never have guessed about the other problems. There was just "something" that kept nagging at me & we decided it would be safer (& less worry for us) if the cats were looked after in the boarding place we'd had lots of previous good experiences with, instead. I guess people aren't always what they appear to be when you first meet them.