Fully understandable.
Found a cockroach on a NYC service bus one day , happily on the plastic seat. Told driver (bad move) - who took the bus out of service there and then empty to the depot in Harlem for deep cleaning and fumigation.
When we did "heavy cleans" on the (admittedly filthy 313's in 1996 on North London Railways) , apart from changing and washing all the removable seat covers and jet washing the floors / washing down the wall panels and ceilings etc, the sets were fumigated first.
Now London is not third world , but the muck that came out was astounding , and guess what , passengers and staff noticed the difference. ! - pleased to say we kept the fleet pretty good internally and externally for a while.