With GSDs more than almost any other breed, this should be a deal breaker. Especially if it's an American line of GSDs... they've bred the dogs so angulated that there is already stress in those areas, so lack of attention to testing/breeding for sound structure would be very alarming to me. OFA tests are a minimum.
I've had 3 GSDs in my life, and while the first was the best dog in the world, it was a real heart breaker to lose him at the age of 7 and watch him go downhill for a year before that. He should have been in his prime!
If you can, I'd go for the german-bred GSDs... they aren't as angulated. We didn't really know what we were doing when we bought our last GSDs, stumbled on them by luck really. Both parents were cop dogs, so from Germany and tested/cleared for everything. The working german GSDs are far less angulated and both of our dogs from them lived a good long time without structural problems... female was 15 and still fine in the hips!