Difficult to say really. If you are not open about your address people are spooked. I can only say that you do tend to get a feel for someone who is serious and someone who isnt. But, I think its all part of the job. You have to show to everyone, you never can be totally sure if they are buying or window shopping,

Dont take it personally, if they turn up or not is up to them; all you can do is present your cars the best you can and treat everybody with courtesy. If someone wants to spend two hours going over your car with no intention of buying they are wasting their time as well as yours.

I have to add that even time wasters are better than not having the phone ringing at all. Its nice to show your cars to somebody! 

Look at it another way. If you were a butcher. You'd get up at 6am. Drive to the shop. Taken in the deliveries. Bring out the stock from the freezer/cold room. Lay out the window display. After all that you stand behind the counter and watch people walk in look and walk out again all day long. Some buy and some dont. All part of the job mate. Dont stress!