I'm always amused when people start talking about "horse hay" because I don't think there has ever been a more misunderstood market on this planet. Please pardon my generalities, but here's how I see it after years in the horse and hay business.
I breed horses and usually have 25-30 of them. All are high-dollar sport horses. I also raise hay to feed the 4 leg combines and sell a little as well. There is a wide variation in what is "horse hay". My version is weed-free, high-protein (mid-high teens), baled at just under 18% moisture. I'm picky about hay because if I can't get the protein from hay (the cheapest feed) I have to make it up with grain/pelleted feed. My feed bill usually runs around $300/week....I'd rather it wasn't any more. I've got friends that are pickier than me who import Timothy hay from up north by the truck loads. We are just one segment of the market...horses are a business.
Another large segment is the " competing horse owner" market. These are pet owners, but they use their horses in various disciplines and compete on them. They worry about feed, but their criteria for horse hay is usually "looks good, smells good". They know names like Tifton, Coastal, Timothy, don't know what they mean, but usually have opinions. They are willing to spend to get what they consider to be decent hay. Most have limited storage and usually buy 10-20 bales at a time.
Then there is the "pasture pet" market. Their horses are lawn ornaments. They look after them, ride them sometimes, leave them on grass, and keep them fed. They usually know little about hay and will buy what's available when it's available.
The worst ones are the ones who have a mare that they breed to keep their Ag tax exemption and sell the foal cheap or at auction. If they buy hay, they'll buy the cheapest junk they can find....they call it "horse hay" 'cause they feed it to a horse. It's usually old and weathered.
With hay, beauty IS in the eye of the beholder. If you bale something up, you can probably sell it as horse hay. Even more so this year. With the rains in the north and the drought in the south where will likely be a hay shortage this year. Bale away, someone will buy it!