Inspired by Ali's post on this subject, thought I would add to the discussion.
Leaving the seat up. What is the big deal here? It is up or it is down. Set it how you want it when you arrive, do not expect someone else to pre-empt who will arrive next and how they will want it. Nobody complains when they switch on the TV and find it is not on the channel they wanted, do they? They just turn over. The same logic should apply to toilet seats!
Worst toilets. These must be some that I found in Malta. At first I thought they were great, as there was an attendant there who kept things clean and clearly prevented graffiti and vandalism. The I went into the cubicle (hey this door is pretty low), shut the door and sat down. Hm, the top of the door was only just above head level. Oh well, on with the task in hand. Then the attendant started talking to me. Nice day, where are you from? Oh, I have got a sister in Kent, blah, blah, blah. As he is talking I notice his voice is getting louder. Looking up I see he is standing right there, looking at me over the top of the door! What is he, a politician or something (woo, satire!). Luckily at some point he took the hint that I was not going to chat to him in that situation and retreated, allowing me the scant privacy that the stupid little door offered! So, if you go to Malta, watch out!
As for British public toilets, they tend to be totally disgusting, having all sorts of stuff on the floor and walls (use your imagination, it will not be worse that the reality!) plus the added joys of discarded needles and the occasional bit of p0rn - I always check before the kids go in - those that will actually use them, that is!
Star Wars - an alternative scene inspired by Ali's response to the above.
Princess Leia: You could not turn Luke to The Dark Side and you will not turn me!
Darth Vader: Well I suppose you must be right. Another drink?
Princess Leia: No thanks, I have had enough already. Where is the toilet in this place, I need to pee.
Darth Vader: Out of the door, second on the left.
Princess Leia: You left the seat up. I CAN'T BELIEVE IT, THE MOST POWERFUL MAN IN THE UNIVERSE LEAVES THE SEAT UP!!!!
Darth Vader: Yes, give in to your ang - OW, NO, SWEET JESUS HELP ME, AAAARRRRGGGGGGHHHHHH!!!!!