say " at this time we are not open for visitors except for families with an approved application adn deposit. I am sure you can understand that with this being such a popular breed we get many requests for visitors and if we accomodated them all we would have no family time for ourselves, in addition to it compromising our personal safety and that of our puppies.
When "xxx" dog has been bred and is expectign puppies then you are welcoem to submit an applicatoin at that tiem and if we both feel that we'd like to proceed then you can submit a deposit and arrange to meet the parents at that time. If you are not happy with the parents or the surrounding at that time then I will be happy to refund your deposit.
If you have open houses/romps then I woudl list when the next oen is and invite them to attend. some people are more pushy than others, the really pushy ones I nicely explain that I prefer to work with families taht understand the importance of family time and are willing to respect boundries and I refer them elsewhere.