Maybe it’s just me, but an unsoundness in an aged race mare does not impact my opinion of her sporthorse broodmare potential in any way whatsoever, which is why I didn’t even feel the need to comment on the hitch behind.
Of course, it all depends on the individual and the situation. If she’s unsound because her hind end conformation is accurately depicted in the 3rd picture (as opposed to other impressions I got from the 1st picture and video) and she can’t hold up to anything, then that’s a different story. But a racing injury? NBD to me. There’s no way to automatically distinguish which it is without more information.
One of the best TB sport broodmares I ever knew was a candidate for euthanasia when she came off the track because she was nearly crippled from bilateral sesamoid fractures. But that was a racing-specific injury unlikely to be replicated in even the highest levels of sport. She was rehabbed and went on to produce many successful foals.
I think conversations about horse purchasing on the internet often make it seem like the decision is black and white, like it’s an automatic yes or no based on the ad. In reality, no situation is that perfect or clear cut.