Among German breeders/collectors this practice is not appreciated. The comments I saw were mostly complaints about the fact, that it simplifies misnaming of semps and that none of the (living) breeders (e.g. Martin Haberer) was ever asked if he's okay with his semp creation being re-named and sold under a different name.
Even if there are no plant patents pending, it's still a question of politeness to ask, I think.
