HI @MaryLynn3 , if you have reservations that are automatically approved you are using Instant Booking, correct? You can set your requirements to have reservations only instantly accepted if guests have previous reviews (under your booking settings.) All others will have to request to book with you.
Keep in mind that all guests have to start somewhere. There are plenty of great guests out there with no reviews. There are also guests out there with good reviews that many not be suitable to your hosting style/space and in turn you would give them a bad review. I say this because everyone's hosting style is different. You may give a guest a bad review because they did not communicate with you and I might not require any communication from my guests, so they would get a good review from me. A stained towel may not mean the same thing to you as it does to me. My point is, is that I don't rely on reviews, they don't tell me very much. I rely on the initial communication with a guest and how polite and informative their message is. From there I can usually tell how the hosting experience will go.