Do you decline a guest who has no reviews?

[Hong Zhu]

I got bad experiences recently with guests who have no reviews. Both of them seem playing the same game. They complained that the house was not clean. For example, hairs in the bathroom, bedroom and even on the bed sheets. They sent me some pictures and asked for discounts. I know my cleaning lady for a long time and she is great. Should I just decline guests without any reviews? I really appreciate your suggestions.