Well it's funny you should say that, I used them last week, and I still think the OP is trying to tell us something :D

In Edinburgh they prefer a more "al fresco" style on Calton Hill.

Now a successful beauty salon.

From my limited experience most of the underground facilities in London are in OK condition, especially those run by Westminster. Less scary than some of the mainline railways stations.

Never use a toilet with blue fluorescent lights.

Well, quite. How are you expected to find a vein with lighting like that?

I'll bow to your knowledge of this! :eek:

Yes, I am telling you that I was surpised. I wondered if everybody else had known so I could have avoided it in the first place. If I had partaken, I likely wouldn't have mentioned it on here (or anywhere else).

Known what, though? The phenomenon has been in popular knowledge for a long time - probably thanks to Round the Horne. It's not so prevalent that every public toilet is affected, nor so obscure that the word is only recognised by bona Polari speakers. Unless you live near a visible "cottage" or have a distinctive taste in smartphone apps, you're unlikely to be aware of specific instances.

It's like laybys. Some rural laybys you don't want to use late at night - but that doesn't mean all rural laybys will be the scene of certain late night activities.

Those are the ones! Was wandering down to Middle Temple when I noticed them! Just couldn't quite remember it when I posted!

Any you especially don't want to roll into some laybys / rural car parks, flick your interior light on to read a map, and wind your window halfway down so the windscreen doesn't fog up while you have the engine turned off... just saying!

There's a railway bridge on the way in to Toronto that has blue lighting underneath it. I thought it was to make it look a bit prettier for the longest time.

Indeed, a colleague of mine parked his estate car in an out of the way car park in Bath, intending to sleep the night there (he's young, they do that sort of thing)
his friend got out of her car and joined him, platonic friends, they share tents when camping too. They became aware of cars pulling up round them and flashing their lights, they still didnt twig what was going on but woke a couple of hours later to people peering into the car through the window

I had a similar moment shortly after visiting Westminster Abbey on my first trip to London about 5 years ago. From what I remember there was an underground restroom very close (there's some sort of square out for traffic to drive around, a statue above ground, and restrooms below). I think you may have had to put a coin (either 20 or 50p) in for a turnstile, but I don't remember. Given how I felt, I didn't really care where it was, what else it could have been used for, nor how clean, just wanted to get it over with. I think it may have been connected with an underpass/pedestrian walkway (I think this is called a subway in the UK).

This all reminds me of that scene from Trainspotting -

"The worst toilet in Scotland"