The walls of the loos at the Elephant House in Edinburgh are now so full of graffiti that Potter fans have even started writing on the windows.
Staff at the cafe used to spend hours painting over the messages left by fans but have now accepted that it is a waste of time.
Messages from all over the world are crammed into every inch of the toilets, ranging from words of devotion such as “You taught me how to read, love and believe, thank you JK always“ to the more risque “Tick here if I can Slytherin to your bed”.
Toilet seats are having to be constantly replaced as a result of diehard fans standing on them to try to reach writing space on the ceiling.
The cafe, in the city’s George IV Bridge, is famous among Potter fans as the place where Rowling wrote her early novels in the back room.
One Harry Potter reference in the women’s toilets read: “Happiness can be found, even in the darkest of places, if one only turns on the lights.”
Another tribute reads: “I’d get sleazy for Ron Weasley.”
The messages cover the sinks, sanitary bins, hairdryers and handwash dispensers. Mirrors and even a frosted window have been used as space ran out.
Many of the messages are in foreign languages including French, Spanish, Turkish and Mandarin. Toilet scribblers include “Chris from Ecuador” who “loves Harry”. Another wrote, in red pen, “Thanks for the sage. Love Argentina.”
Elephant House manager, Roxy Hessami, 22, said: “We used to paint them at the end of every Fringe festival, but I don’t think we’ve painted them for three years.
“After it was painted once, a note about who was in Dumbledore’s Army had three tallies next to it, by the end of the day it was at 83.”
Roxy added: “We try to get rid of it from the mirrors. We’ve had toilet seats broken because people have been trying to write things on the ceiling.
“There’s no point spending like £5,000 to have them ruined again.”
“Someone once wrote ‘The service is so slow in here anyone could write a book’, everyone thought it was funny, even the owner, but we had to paint over that one.”
“A year ago I painted the boys’, it took me 14 hours and two nights to have it done, I had to do three undercoats and the following day it was covered again.”
The establishment revealed they have received complaints from customers over the state of their loos.
“Some people do complain, but we have to tell them we can’t control it, we’re so busy, it’s not like we give people pens,” Roxy added.
“But some people bring in pens designed to stay there permanently.”