I want to know what that rug is made of. It withstood the acid way better than the bed.
I believe that may be due to it being thicker, possibly from wool and the fact that the cleaning staff likely goes through the hotel floor using relatively strong chemicals to clean shite up, while the cloth on the bed is usually just tossed into a washing machine with relatively weak cleaning chemicals (whatever the English word is for it).
In short, the rug is made to endure floor cleaners and relatively strong chemicals, whilst the the bed cloths are the kind you usually just put in a washing machines to clean of sweat, grime, bedbugs and usually at worst, wine or food stains.