Let's start at the beginning: Every surface of an airplane lavatory is supposed to be cleaned with disinfectants and deodorizers after each arrival and during overnight layovers.

Airplane toilets undergo different levels of cleaning depending on the flight's duration and the "turnaround" time between flights. During a short-haul turnaround (the 30–60 minutes between landing and the next takeoff), cleaning crews typically have only 5 to 10 minutes to "freshen" the lavatories. This involves a quick wipe-down of surfaces, replenishing paper products, and emptying the trash. Deep cleaning usually only happens overnight or during longer maintenance periods. On long-haul international flights, flight attendants are responsible for "ongoing maintenance." They generally check the lavatories every 30 to 60 minutes to ensure they aren't overflowing with trash and to wipe down the counters. However, they are not professional cleaners and won't perform a "scrub" mid-flight unless there is a major spill. Because of the high volume of users (up to 50 people per toilet on a full wide-body jet), the floor is rarely "clean" by the end of a flight, which is why flight attendants strongly advise never walking into a plane bathroom in just your socks.