@Jillian136 Sometimes when a guest shows that they've had an account for awhile (not new), but there are no reviews, it's because their previous hosts declined to review them. Some hosts can't bring themselves to write a bad review, so they either just post somethng like "Nice guests" (which doesn't help future hosts one bit) or they don't leave a review at all. And some hosts are under the erroneous impression that if they don't submit a review, that the guest's review won't be published. So if they had a bad guest and suspect the guest will trash them in the review, they don't submit one. But all reviews are published, no matter whether both parties write one or not.
But that's not always the case- I've had several guests who had had an account for several years, yet had no reviews. If I see that, I'll ask in a friendly way-"So, XX, I was just curious- I see you've been a member for a couple of years, but don't have any reviews. What's up with that?" For me, those all turned out to be totally innocent- one had joined for a trip that never panned out and had never had a chance to get away for another trip, one said she'd had a couple of stays, but the hosts failed to review, and one said she likes to armchair travel, and had had many stays, but under her husband's account. Her booking with me was the first time she'd taken a holiday on her own. In all those cases, the guests had really good communication skills, and volunteered info about themselves and the purpose of their trip, so I didn't feel the least bit wary, and they all turned out to be lovely guests.
Be aware that scammers who want to party will look for new listings, as they figure the host is green and doesn't know how to vet guests well. There's all sorts of blogs and such where scammer guests exchange their scamming techniques and how to get a free stay. . So you'll have to be especially on guard for awhile until you get a few reviews under your belt and a little more experienced. This forum is a good place to come if you have doubts about a booking, or how to word a review. And you can really learn a lot here. For instance, do a search for threads on "Red Flags" and just read over posts here every few days or so to see what different issues hosts deal with and how they handled it, sometimes well, and sometimes badly.
It's hard to figure out how Airbnb's algorithms work. Like why she'd be prevented from booking, but could send an Inquiry. They do have an algorithm that prevents guests under 25 from booking a last-minute one-nighter, because that's the most common scenario for party animals. That's a fairly recent addition to their platform- since the Orinda and a Toronto "party house" shootings. That may be what happened here. But hosts have had that same thing come up, and the guest was booking for a week, and not last minute, so it's almost impossible to really figure it out.
As for accepting cash, you can get booted off the platform for that. Doesn't mean hosts don't sometimes do it, but not for the original booking itself. I've done it once or twice if a really nice guest just wanted to stay for an extra day or two, and they'd already been here for a week or more, so I could tell they weren't scammers. Not to try to go around airbnb, but just so we didn't have to waste time going online and dealing with it. Once a guest's bookd dates have come to an end, whatever arrangements you make with guests is your business. Just be aware that you won't be supported by Airbnb in any way if something bad happens if the guest doesn't actually have a valid booking through them anymore.