Curious to get the public opinion on this topic....
Say you've purchased some fry, grown them out, and the majority are deformed. What would you do?
Long story short, I'd bought a variety of angelfish from a variety of sources. I bought them through auction, not the direct breeder necessarily, though I'd suspect so. One group in particular has a messed up body shape. The anal fin is offset from the dorsal. They looked ridiculous. I grew them out, they never looked any better, and in the end I choose to cull them. Would you notify the seller?
Personally, I'd want to know if I were the breeder. I strive to produce quality fish and feel pretty good that I haven't passed on fish with inbred genetics. At the same time, I'm on the fence about telling the source. People these days don't take criticism well, so maybe it's best to just not say anything and personally avoid that source for future purchases.
