Maybe it's just me. There are times when I don't smell Louie's urine, and this can go on for days. There are other times that the pungent smell of ammonia can bowl me over. Is this more or less the case with neutered male cats.............the urine scent is more pungent at random times? I think that this is a stretch, but can cats intentionally activate the scent (or whatever the mechanism is) in the urine for marking purposes? Again, a stretch, since, why would he want to "mark" his litter box?