@R1, forgive the lateness - I've not been on since I last posted.
I'm sorry, but your experience in Bournemouth is only evidence of the travellers in Bournemouth. Now, as I said earlier, I have no idea what the proportion of 'good' to 'bad' travellers is, but I refuse to use my personal experience as an indicator of it because that would be ridiculous. I've encountered one group of them in one area of the country at one time. But I'm afraid precisely the same applies to you. You are in no more of a position than I am to make assertions about 'all travellers' - which, please note, is exactly what you have tried to do in this thread. You speak very often of your intelligence R1 - this should be very clear to you. It's a basic principle of critical thinking.
What I will say is that one thing that's notable about the 'nice'/ordinary travellers, or at least the ones that I've encountered, is that if they didn't tell you, you wouldn't have any idea that they were travellers unless you actually visited their site. I wonder how many you've met without realising? What do you think? Is it possible? Can you prove that it isn't?