No better time to get in trouble than your first night on a forum...so here we go. This is sort of a he said/she said kind of thing, but I have been on both sides of this fence myself.
I hunt foxes and annually tan for sale a dozen or so. I also get asked to tan for friends and acquaintances, which I have grown to dread.
When I get back from a nights hunt, I immediately skin, flesh, split tails, remove the majority of ear cartilage, split the lips, peel down the nose cartilage, and get on stretchers, everything that I shot. A few hours earlier they were all running. I take care of my hides before I take care of myself. Tanning my own hides, I have never had any slippage of any kind and they turn out great.
My experience with hides brought to me by others is not quite as good. Overall OK I guess. But I know that the guy that just shot his first coyote probably took it to work or down to the fire hall to show all the guys. (I know that happens because thats what I did with my first one!) If the guy doesn't skin and cool the hide immediately, he is already on the downhill side headed for problems. The proud hunter probably doesn't have a fleshing beam, or a fleshing knife, or a stretcher to put the hide on to keep it from laying on itself till it drys.(Salt or no salt.) (Properly cared for hides need not be salted.) If you don't have the expertise or means to process a dead animal into a top quality hide, there are two routes to getting the best result possible. Depending on the value you put on your trophy, I would find either a reputable taxidermist or a local trapper that routinely handles hides like the one you have. Both know what needs done. I would skin and help all I could to save a trophy for a guy.
I was taught a long time ago that in order to have a top quality hide, you need to take better care of the hide than you do of the meat. The hide is certainly more fragile and prone to spoilage than the flesh. There are no magic chemicals that the tannery can add to the broth that will make the hair stick once the bacteria have had their shot at it.
Thawing a frozen prime coyote hide is in itself a daunting task for a guy that is bacteria concious. The subject of another whole thread.
It's not impossible that there were problems at the tannery, but hold the seller and the buyer to equal standards when you make your final judgement.
Tom