The worse case I personally encountered was in an Angel Airlines
plane (no longer in operation, their cabin crew, male and female,
could easily qualify to walk the catwalk... for airline cabin crew,
really good looking until 
).
One stewardess tried to clean it and sprayed lots of air freshener
but you know how sometimes, when you try harder it makes it
worse?
You disturb the air and the smell simply spreads further...
