I bought this toilet for a new installation.... this toilet has a very poor glazing on the toilet bowl itself.   The bowl forms a calcium water ring repeatedly.... has had this problem since it was installed.  Even using toilet bowl cleaners, you often have to scrape with a razor blade.   I have 2 other older Kohler toilets which do not have this problem. Usage is about equal between the three toilets.... same water source.  And yes, the lid on the tank does not fit properly.. unglazed line shows.