click on the picture of that person, the profile should come up, hopefully with a brief write up, the list of verifications, and their reviews. If there are none, it either means they have not been a guest or host before, or nobody has given them a review. It doesn't necessarily mean anything "bad", but if I had guests that were forgettable, neither bad nor really good/fun, I tend not to give a review - unless they write one for me, then I return the favor.
Yes, I always try to find out as much as I can from a potential guest. As we don't get the last name until the booking is completed, yiu can't google them . The obvious way to find out more it to engage them, briefly, in a conversation back and forth, like, "so where else have you traveled on Airbnb before", just friendly chatter. their response time and overall tone will tell you a lot! My husband is always amazed how I tell him before a guest arrives, this one is fun, this one will be slightly difficult, etc.. and so far I have always been right on the money....