Not everyone who is pagan damages ancient monuments.
Many are just as horrified by such destruction. They may go to stones to do rituals but theirs are non destructive.
Coldrum in Kent has had the same problem. One pagan was so fed up with the mess that he took it open himself to go down as often as possible to clear the mess away and report any damage to the authorities. People were leaving plastic flowers and one day he arrived to find someone had covered the monument in sand and seashells.
The same is happening to some Holy wells around the country. Fair enough in the past bits of rag would be tied to trees by such wells but the rags were of cotton or other natural fiber which would rot away. Nowadays man made materials are used which don't.
If people do want to go to these sites for spiritual reasons ( as I have done myself) I wish they would think a bit before they go. Is it really necessary to stick candles to stones and leave a mess of wax all over them ( I've seen the mess they cause while visiting West Kennet long barrow), do you really need to draw symbols on monuments, or dig holes. As for offerings, think about it. Plastic and man made fibers do not rot as easily as natural products. If people must leave something then maybe a few wild flowers laid at the base of the monument and outside of burial chambers.
And most important of all, respect others who are visiting the monuments. They have just as much right to be there. Pagans do not have a monopoly over ancient monuments. All of us whatever we care to believe in have a right to go to these places. And I'm sure that we would all like to see them at their best and not damaged and covered in rubbish.
Something is not right. This message is just to keep things from messing up down the road