Homer Do you have some information that the rest of us have never seen or heard of, or are you just taking wild guesses as something you obviously know little about. do some research and reading. 5 ppm ammonia will not burn a fish's skin through the slime coat unless that fish is for some other reason unhealthy. 5 ppm ammonia will definately not harm a snail, and I imagine much more would not either.
beforte you start accusing someone of poor practices it might be wise of you to actually do some research and learn some things.
This is not new information, this is not hard to find information. Snails are not affected by ammonia.
On top of that, contrary to your statement Nitrite does not burn a fish's skin or gills. Nitrite blocks the ability of the fish's blood to carry oxygen. and as said since a snail doesn't breathe underwater, nitrite has no effect.
So you can take the nitrite part clear out of your equation and then do your research on ammonia only and save yourself some time.
And of course you could do just exactly what I already suggersted and test it yourself. It's simple, easy to do, and if you have ever owned snails, you should know enough about their normal behavior and their defensive behavior to see that there is no difference with or without ammonia.
MTS's can and will close up their shell and wait out a copper treatment, anytime they are exposed to anything noxious, the close up and stay that way until it has passed. Pond snails alter their feeding activities, and their breeding activity both, Ramshorns do likewise. any apple snail will completely leave the water when presented with undesireable conditions. None, I repeat None of these behaviors manifest when these animals are exposed to ammonia at cycling levels.
My experience was not gained without research first, I do not advocate harming my aquatic pets or anyone else's, but I do not simply devise answers for folks without proper research either. I first asked this question several years ago while doing a fishless cycle in a tank that had snail eggs in it. ?The consensus among knowledgeable snails keepers was pretty strong. So then I did my own testing, and reinforced the knowledge they had given me.
I know will once again suggest you actually try the experiment, and research the subject deeper.