I haven't started my serious horse shopping (going an looking at horses in person) because I don't have a place yet, so I would never be one of those checking out a horse for the sake of getting a free ride.
This will be my first horse so if I had to bring my own saddle, I wouldn't be able to. I'd have to pass up looking at your horse if I knew I wouldn't be able to ride it even if everything else looked good (ie: ground manners, appearance, personality).
Also, I plan to ride any horse I am really interested in more than once. So if I was buying a horse from you, I'd look at the horse, have you ride it, then I'd ride it, then I'd probably stick my kid on her for a minute, then thank you and arrange to look at the horse again another time.
From everything I've gathered from reading other peoples stories on HF, I'll probably have to test ride more than 10 horses before I find the right one. The people riding with no place to put a horse or just to get a free ride are stinkers, but I might end up wasting your time too because the horse wasn't right, or I see an even better one a few days later.
Also, I can't see how a twenty minute ride on a horse is the same as taking a dealer's car for the day.