@Lisa990 Yes, ask some questions in a friendly, chatty way and see what kind of response you get. I'd also make it clear that only she and her mom will be allowed in the unit, not her boyfriend. Otherwise, you could find him coming and going as if he has paid to stay.
I've accepted numerous guests with no reviews, but their messages when requesting to book were nice, articulate, and informative (except one, but I prodded him a bit and he was instantly forthcoming) and they all turned out to be great guests. However, it defnitely pays to be cautious.