Please don’t take this the wrong way, but the most likely reason for the condition you describe is that someone is peeing outside the bowl. Such smells usually emanate from urine soaked into areas around the base of the toilet, especially if you have a vinyl floor covering instead of tile. Clean up the ouside of the bowl and the floor around the toilet. If the urine has soaked into the flooring, you may need to pull up the covering and disinfect and sand the floor.
Then put a sign over the throne that says “We aim to please our guests. You aim too, please.”
NtP