Last week I used the lav on a flight and saw that the sink was clogged. Naturally, I used the water from the faucet sparingly, hit the stopper a couple times to no avail, and then silently slinked back to my seat. I sure didn't want the FA to assume it was me that caused the problem.

I imagined walking back down the aisle after alerting the FA, then hearing an announcement over the PA: "We'd like to remind the passengers not to discard hand towels into the sink or toilet, since doing so WILL cause a blockage." The trip back to the seat would then become a "walk of shame." The accusatory stares from the fellow pax, hushed murmurs of "what a jerk," or just "eeewwwww!"

It's just better to ignore the problem.