My family owned two impressive bred mares. They were both N/N (said so on the AQHA papers) and we didnt have any major problems with them other then they both had the tendancy to get a little high strung at times. One mare we did cow work and gaming with and the other one I showed in pleasure events.
When it came time to sell some people would see impressive and run. It is really stupid that people have that mind set when the horses have been tested and they are N/N but it is totally personal preference. We didnt want them for breeding so when we bought them we got them because of their ability not their papers(after knowing they were N/N).
I do hate though when people try to keep the one positive in there so that they have a better halter horse...but in some cases that is all they will ever be....halter horses