One of my dislikes: people not changing the toilet roll when they have used the last piece of paper.
I mean you are just sitting there, doing whatever, so why on earth wouldn't you put another toilet roll (if there is one there) on the holder.
Worse is when they put the new one on the floor or rest it on the holder and leave the empty roll on the holder, I mean if you can be bothered to put the new toilet roll out, why on earth wouldn't you put it on the holder!!
And here's another one, the toilet roll is empty so just throw it on the floor, no need to put it in the bin, oh and while you're at it, just throw all your empty tampon wrappers on the floor as well, or just sit there and tear little bits of toilet paper up and throw them on the floor.
Then there are skid marks in the toilet, but that's the cleaners' job you say, well I say have some respect for the next person coming into that toilet after you, and have some respect for the cleaner as well, they seldom get any thanks and they are the ones cleaning up after you.