I like buying "copies" of stamps or whatever the seller calls them. For many stamps I'll never be able to afford, this is the only way to fill a space. Of course they need to be labeled as such. The whole subject of fakes and forgeries is inherently interesting in addition to being useful to collectors. It has a clear history, as well. So yes it would make for an interesting topic and perhaps also help prevent fraudulent sales. There are posts asking whether a stamp is a fake, so why not gather them into a separate topic?
We had this discussion on the coin forum years ago and decided it would be much more beneficial and organized to have counterfeits in the same category they would be in if they were real. If someone comes here to research a classic US stamp, and its counterfeit and they don't know it, they still go to US classic stamp forum to try to learn about. There could be 20 topics on his exact counterfeit stamp but they'd be off in a different forum and he'd never see them.