Why do one-piece Kohler toilets smell no matter how clean ?

Cleaning and scrubbing don't get rid of the odor which is only noticeable on one-piece Kohler toilets.|||Which piece smells? Probably not the toilet, probably your plumbing or you need to install a new wax ring.|||Because Kohler is French|||they are madein china|||Take an actual lemon and use it... much like in a sink drain I place one in disposal and run it... smells nicer for days. And worst case I clean whatever it is with bleach! Bleach kills all icky germs and smells...