Purchased a new 2014 Rockwood Trailer a few months ago. The odor kept building around toilet. Changed chemicals, took time to use wash down, nothing worked. Decided to pull toilet and inspect seal, flange etc. To my shock the lower part of the toilet was full of black water. The toilet is a Dometic model 300 which has a 2 piece base. The seal was leaking into the void. Called Demetic they sent me a me a new toilet under warranty. Smell is gone.