Are you under the impression that everyone has a social media presence? Profile photos are hidden until a booking is confirmed, to supposedly cut down on discrimination, like declining a guest based on the color of their skin. There's a lot of debate about that from hosts, and even guests, as many guests have said they'd much rather be declined by a prejudiced host than book a place only to arrive and get some bad vibes (not to mention not wanting to put money in the pocket of that kind of host).
However, I do agree that if a guest were to have a profile photo of themselves with a gun, or barely clad, or making some rude gesture to the camera, that would be a guest I wouldn't want to accept, simply because it indicates a level of cluelessness as to how to present oneself when asking to book someone's home.
But it's a guest's behavior in your home that's really the important part, isn't it? I don't happen to like gun lovers, but as long as they didn't bring a gun into my home, and treated me and the home with respect, their personal views, interests, etc, aren't really my business. A woman could be a sex worker, but as long as she doesn't turn tricks in my home, and is a good guest, why would I care what she does for a living?
And there's nothing to stop you from asking a guest for their full name after they've booked, or asking them to please upload a real profile photo if you see that all they have is a picture of a cartoon character or their cat.
I judge whether to accept a guest based o the way they communicate with me, as well as their past reviews, if they have any. It's never occurred to me to look them up on social media, which I have an aversion to anyway.
@Eileen333