I don't cos I'm not a racist but I have heard a colleague and a friend use these sorts of terms. They are both people who will denigrate Muslims as a group too, use the term chav freely, basically racists / snobs / people very suspicious of anyone 'other'.
I do think they and others are more willing to insult gypsies and travellers than other groups, more openly and casually, and would not see doing so as racist. I think the reason is that they view (and experience) travellers in terms of travelling - as a behaviour, not as a group (and probably have no experience of gypsies at all).
Then, because the only aspects of that behaviour that come to anyone's attention are negative ones.
The flip side of that is that positive examples - like you OP - don't bring themselves to anyone's attention. Also, gypsy culture isn't taught in schools, as far as I'm aware, in the way that aspects of other cultures and religions are.
So people's only associations with these terms and communities are negative behaviours. That is tied up with old-fashioned prejudice, ignorance, lack of experience, to form a casual prejudice that is often not challenged in the way that other racism would be.