Ohh yeah and the "Hair Setting Solution" is basically a bacteriacide that kills bacteria on a cape. It doesn't actually "set" the hair. It is either alcohol based or a mild acid based. I have used Stop Rot before on iffy capes but I would not say it "saved" an iffy cape that salt wouldn't have done.
Each skin, wether it be a cape, hide, or fur is individual. There is no way of telling what types of bacteria are on your animal. Sometimes an animal can be sick or have a disease but to you and I looks healthy. There are a lot or different factors out there that can affect the quality of a cape. Also the type of animal itself can play a huge factor. is it a small game animal? Big game animal? Is it a predator? Is it a small game predator (bobcat coyote, etc)? Some animals are more prone to slipping that others just because of there hair root structure and the type of bacteria they are exposed to.
All those field care guides and instructions that taxidermists hand out. Even if you follow them to a "T" they are not a 100% guarantee your hide will not slip. That is why most taxidermists put in there contract "We do not guarantee tanning".
Now just because I said that doesn't mean get lazy and go well if following it isn't a guarantee my cape will make it than I will leave it in the back of my truck for a week.

By following those field care guides of instructions you are helping to ensure your cape will make it through the tan but there will always be a hide here and there that will leave everyone scratching there heads as to why it slipped when everything was supposedly done "right".