puzzledandpissedoff in answer to your plea for good experiences with "obvious" Travellers/Gypsies...
15 years ago my DCs primary school was the local designated school for Traveller children of families staying at the camp up the road from us. Most of them were lovely kids, my DD's best friend was a Traveller child, DD went to hers for tea and to play, the place was spotless and her mother was friendly and civil, just as you'd expect your DC's friends parents to be, Traveller or no. One of the mothers was a gobshite, and so were her kids, but given that the other Travellers avoided her as well, I suspect she wasn't a gobshite because she was a Traveller, it was because she was a gobshite and a crap mother.
More recently, Gypsies would camp every year on the verges of the village I lived in, generally for the same weeks at the end of May, beginning of June. Kept themselves to themselves, but when they left, the only sign of their having been there was a single black bag of rubbish, which the council collected. No vandalism, no excrement, nappies or sanpro.
On the other hand, I've seen places where Travellers have stayed for a couple of nights left like a bombsite. I tend to the view that it's probably some families/groups don't care or even get a bit of a buzz about being the antisocial ones, but it's only some, not all.
So, in my contacts with Travellers/Gypsies, good experiences have tended to outweigh the bad. I don't think it's appropriate to suggest that my experience is anything other than my experience.