@Lincoln6, it isn't just that it is against the rules (which it totally is).
It is also just a bad idea for you.
Based on stories from experienced hosts, the more experienced the host, the more they are against letting guests "Preview" the listing.
They have said:
1. "Preview" guests often just want to meet you to ask for a discount, or to propose paying outside the AirBnB system. Both bad for you.
2. "Preview" guests are often the worst kind of picky, hard to satisfy guests.
3. "Preview" guests might be criminals just wanting to case your property before robbing it. Or just robbing you if you are alone with them.
4. It is huge waste of your time. Often hosts will wait hours for late "Preview" guests who just ask for a discount and then never book.
5. What exactly are they going to learn from looking at the listing that your many lovely pictures don't already show?
If they want to learn something more, why don't they just ask you?
If they want to see the neighborhood, they can see the neighborhood without coming inside your property.
Don't do it.
Tell them "If there is anything more you need to know about the listing, I am happy to answer all your questions. If you want to look at the neighborhood, our closest intersection is (street & street). We do not allow unbooked guests inside the property."