Please leave this toilet as you would expect to find it.
Can you see the flaw? When I go into a public toilet, be it in the middle of London or at work, what I *expect* to find is a toilet that hasn't been flushed in three days, stuffed to the gills with toilet paper, overflowing, or pristinely clean, except for the single rogue turd left floating proudly in the middle of the bowl... which, despite these signs having been put on the stall doors at work over a year ago, is still invariably what I find.
This is because the wording of the sign gives overly literal men a logical get out clause: they *expect* to see the toilet left in such a state that makes the bog at the beginning of Trainspotting look spotless. So that's what they leave, because it's a public toilet and they're not the one left to clean up the shit (literally).
What the sign should have said was this:
Please leave this toilet as you would wish to find it.
A change of only a single word, but a huge difference semantically, because no-one, not even a man, would *wish* to find a filthy toilet waiting for them when their bowels are bursting... It kind of makes you wonder if they use the same signs in the ladies toilets, and whether it makes any difference to how they leave their cludgies. I'd guess probably yes, as women generally aren't quite such pedantic jerks...