A lot of these products do have an appropriate use, though generally a very narrow range of usefulness. For instance, Jump Start as mentioned. It's corn syrup. This can be useful to pep up a very weak animal, get them strong enough to take real food. With reptiles, I don't think I'd use it on a pure carnivore like a snake, but if you had a very weak baby iguana, a bit of Jump Start might get him going enough to eat some fruits or veggies and get some real nutrition. They sell the same product for mammals, and it's very useful in certain circumstances (hypoglycemic toy puppies, for instance). But you don't give it to your dog every day. I'm annoyed that these things are recommended by pet store employees as often as they are though.
Yeah, having ferrets will teach you that most pet supplies are either harmful or useless. Jeez the junk they sell for ferrets is appalling. Pro tip: if you get ferrets, don't buy anything from the ferret section. Seriously. (Actually it's a little better now. They actually have some decent stuff. 20 years ago when I got my first ferret it was all trash).
