Sadly I think you are right. I know people do mark hogs from posts on Hedgehog Street but i’m not a fan. Last year one hog turned up with a large patch of white on its side which was almost certainly someone marking it. I know it has been said before but they are wild animals and, if you observe them closely, you can tell the difference without the need to paint them!
Hopefully whoever marked them at least used something appropriate. If people are going to do this a few spines would suffice to mark the hog not undertake artwork on them.
Anyway off my soapbox now and interesting about the chin rubbing. I have certainly seen the hogs elongating their bodies and also rounding their bodies and going up on their toes – all interesting behaviour that I don’t fully understand. Also enjoy watching them scratch with their almost seemingly extendable legs sometimes leading to a comical sideways fall! i will have to keep an eye out for the face contortions in future though.