Assalamo Alaikum Wa Rahmatullah, You're correct. Alahazrat RadiAllahu anhu gave reference [Sayyidi Ahmad Tahtawi Misri in the Hashiya (marginal notes) of Durr Mukhtar] illustrating the point that "If there is a Mawdu' hadith regarding a particular act then that act will ONLY be prohibted if it's contrary to the principles of Shari'ah. If not, then the act comes under the Asl al-`Aam [The originality of all things is Mubah (permissible)]. Thus, even though there is a fabricated [Mawdu'] hadith related to a particular act, it will not be regarded as prohibited [Mamnu']."
correct me if i'm wrong but this excerpt from alaHazrat's muniru'l 'ayn says that even if a Hadith is fabricated, if the action mentioned therein is not against the shari'ah, then it remains on its asl and the asl of all things is that al-aslu fi'l ashya' al-ibaHah -- everything is mubaH in the first instance
