I have had many people stay wih me who were newbies and now would have a positive review, I can only think of a couple of occasions when I gave a negitve comment. So they would by your definition be good to go.
However most of my stays are for one or tow nights and I am on the premises.
I would not wish to suggest anyone who had stayed with me would be good to go in your situation.
Let us say somebody did have evild intent, they could stay somewhere, het a positive review and then would be good to go.
Now if this is your rule I would make it more prominant, maybe one of the first items.
David