On an AA flight MIA-JFK, a passenger brought their absolutely enormous dog up from economy to the forward toilet during the flight. I was torn between digust and rationalisation that aircraft toilets are already unspeakable and at least the owner was there to clean things up. Thankfully it was not seated anywhere near me; I would have objected simply because of its size, there was no way it was going to fit under the seat in front or around one person's legs so it would have been a significant annoyance.