Well, they're not really "knock-offs" which are poor copies of something, fakes if you like, designed to look like the real thing. They are similar products in competition with Playmobil. After all, one Western saloon is very much like another whoever makes it.
I was referring mostly to stuff like mega-blocks, which is considered to be a lego knock-off.
But on the bright side, Playmobil is aso located near discovery channel toys, lincoln logs, brios, and the like -- toys that are generally considered to encourage imagination and be sort of "smart kid toys." So I guess that's a really good thing.