I only advertise in the off-campus network with the local colleges and universities. All initial contact is via email.
I have a "standard" response pre-canned. I change it a little bit to fit the circumstances...but..I ask all the questions in a sort of a 'chatty' way. If I don't like the answers, I just tell them to keep looking.
I then make an arrangement to meet with them and their parents at the house or unit. I must meet everyone in person. This is usually kids who didn't get into the dorms and the kids and parents are in town for the look-see week and they are all trying to get the "little darlings" settled for the coming year. Since the parents will be on the lease..I must meet them