Not buying them! Antiques are one offs so if you see something and have a positive reaction to it then just buy it, before someone else does - you'll find somewhere it can work, and if not, you can sell it on. The only antiques I've ever regretted are the ones I didn't buy.
On a more practical note I think asking for a condition report is important if you are buying something without seeing it in the flesh. If you do have the opportunity to see it in person then open all the drawers, look underneath, look at the back of the piece, have a really good poke around! Then make sure you are happy with the condition of the piece and that the price relfects it. If you only want to pay a few hundred pounds for a chest of drawers then you should accept that there will be marks on the top, veneer chipped off and probably quite a tatty back to the piece, but that's fine as it's lived a life before you and it's condition is reflected in the price. However, if you are paying upwards of a thousand pounds then you would expect the piece to have been sensitively restored and in good working condition.