I also have sometimes accepted these kinds of inquiries, on condition that they've answered all questions I've asked them to my satisfaction. I also ask them to upload a profile photo, or at least tell me how I can find them on social media. Words like "Facebook" and "Twitter" get blocked out by the messaging system but it's easy enough to figure out what platform they are using depending on the info/username they send back.. I do this to verify if they are who they say they are.
There are a lot of first time Airbnb users and they don't have reviews but that doesn't automatically mean they are a bad guest. And about the one liner intro, I try to remember that this is in response to the standard prompt in the messaging system "Tell [host] a bit about yourself and your trip"... some are just kinda lazy to say something about themselves (especially if typing on a mobile device) so they just quickly say what the trip is about.
It's a bit of more work involved to try and prod the guest for info. But usually they are just so used to online booking platforms that don't ask these questions, and/or they forget that they are staying in someone's home and not a hotel, so they need an extra push to open up about themselves.
Use good judgment though. If they are still being vague and/or dodgy even after you ask them questions, then it's probably best to decline. Happy hosting