Repeat the inspection from directly behind the horse to detect hip and stifle trouble. A horse is an athlete and, as such, must have enough muscle to perform well, but the muscle must be of the proper kind. Avoid the horse with short, bunchy muscles if you are looking for a mount with agility and sustained speed over a long distance. Next, examine the horse from the side. Shoulder and pastern angles and straightness of legs are of major importance in this view.
Chances are good that a long-backed horse is a poor keeper.
The shoulder is probably too straight as well. White marks at the withers or just behind the elbow indicate that the horse has old, healed saddle galls and girth chafes. There may have been problems in the past in fitting a saddle and keeping it in place. Lack of balance may not look the best but may not detract seriously from the horse's performance unless it is excessive. Remember that the main power and thrust comes from the rear quarters and deficiency here is the most damaging.