@Pete69 I think what is meant by no negative reviews would relate to low star levels, maybe? Or that if a guest were to IB and a host read their reviews and found negative ones they could call Airbnb and present that as a valid reason for cancelling without penalty?
Even if a guest only had one review and it wasn't negative, I wouldn't consider that much to go on. We all know there's a lot of hosts out there who don't leave honest reviews, as well as off-site hosts or property managers who never even meet the guests. As long as the house wasn't trashed, they get a "Nice guests." review.
While I do definitely read guest reviews and have zero qualms about accepting a guest whose good reviews I can tell are honest (home-share hosts who actually write quite a bit about how great the guests were), I've accpeted quite a few guests with no reviews. I go on their communication style, which tells me a lot. They've all turned out to be fine guests.