The intent of the website is to introduce you to RVers with similar interests as yours. It is totally up to you who you wish to accept or decline. When you get a request, click through to view the requester's profile and decide if they meet your criteria.
You will set maximum RV size, the number of nights, whether you welcome pets, and any other restrictions when you create your profile. You can add any house rules you like (no smoking, pets must be on a leash, etc.). Guests are reminded of your restrictions and must agree to them in order to send a request. Update your rules and change your permissions and restrictions as often as you wish.