He's really a pretty boy, but I have to agree the way his hooves/feet look and the way he stands makes me worry. Horses can be given something called phenylbutazone (aka "Bute") to treat and sometimes cover up signs of lameness. Sometimes someone selling a horse will give this to make the horse seem fine when a buyer comes to see it. Here is a bit more about phenylbutazone:

http://horseproducts.stablemade.com/...ylbutazone.htm

The way that his back heels look so short and "clipped" and his front hooves look long in the toe part makes it appear that he stands that way often. He is certainly a beautiful and gentle looking horse but be very careful, it would be heartbreaking to end up with a horse that required a lot of specialized vet care, specialized shoes and hoof care, and constant pain medication to be able to ride. Best of luck with him