Greetings @Rebecca676:
I had the same concern as you when vetting guests. I happened upon a similar topic while browsing an Airbnb-related site. The poster mentioned this article from Forbes magazine (https://www.forbes.com/sites/sethporges/2017/07/27/all-airbnb-hosts-should-use-this-chrome-extension...).
I checked it out and learned about an extension called AirReview. I love it! When guests have previous reviews, go to their profile and this extension automatically searches through all their hosts' past reviews to see if that specific guest left a review. If so, it is posted immediately below their review of the listing. Otherwise, it states that the guest didn't leave a review.
The extension is available for Chrome and Firefox web browsers at this time. I use the Firefox version. Hopefully they'll expand to mobile apps and other browsers in the future.