I guess this isn't really a "pre-purchase" question. But can anyone tell me what dealer prep fees are supposed to cover on a used unit? We just took delivery, got it set up in a difficult ( non-full hookup) seasonal spot, only to discover the tanks are full of stagnant, disgusting water! Is flushing those tanks not considered "prep"?? They definitely didn't clean the inside either so idk really what I paid for.