New listing, no sitter reviews yet. is it a scam?

I don’t think a scammer has much to gain from THS, as it’s mutually free exchange with a very high joining fee. There is no way to research an owner - this would be against privacy policy.

What I would say though is that if something doesn’t feel right, go with your gut and don’t choose that sit. This doesn’t even necessarily mean there’s anything wrong with the listing or owner, may just mean it’s not a good fit.