Nellydean
Thanks for your question. I grew up in a part of the country with a strong Travelling community.
I'm very conscious that language I use might, inadvertently but still unacceptably, cause offence, as I'm not part of the community I'm talking about. So I hope I express myself correctly.
Because the Travellers are an ethnically distinct population, they do 'look different'. Where I now work, I can tell by looking at someone, if they are from the Travelling community. It's nothing to do with their speech patterns, clothes (no idea what OP even meant by this anyway) or other signifiers.
You say you can't, but perhaps because I grew up knowing a lot of Travellers, I can.
It's so reductive & ignorant of OP to assume that Travellers can easily, should they wish to, remove themselves as subjects of prejudice. Sadly, especially in Ireland, it's not true.