Three or four years ago it was the Russians; now it's the Chinese.
What they have in common is that many of the groups consisted (or consist) of first time tourists, beneficiaries of the economic up-turns in their respective countries. Some of the Russians I saw in Central, for example, had little idea how to deal with Thais, often looming over them and making the women particularly uncomfortable. My suspicion is that many of the Chinese have not been abroad before and like the British package toruists of the 70s when that industry "took off" have yet to learn how to conduct themselves in a foreign country. Come to think of it, some of my countrymen still don't how to believe in the places like Soi 6.
The Chinese tourists I see here in London- a much more expensive trip- are seasoned travellers and present no such problems as far as I can see. They happily spend vast amounts in Harrods and Fortnum & Mason's and behave just like any other rich tourists.
In Chiang Mai, on the other hand, much closer to home and therefore much cheaper for the Chinese visitor, the conduct of one guide and his group in a temple my boyfriend and I were in last January was astonishingly ignorant and insulting to Thais. Less significant-perhaps even slightly amusing- our hotel in Bali a few months ago was used as an overnight stop-off for Chinese groups and the noise at breakfast (they'd left by dinner) was astonishingly noisy.
Its 'possible that these problems- and I've heard more complaints from Chiang Mai than Pattaya- will lessen as the visitors become more experienced in foreign travel. Not that this has improved the behaviour of some of my countrymen when confronted by cheap women and cheap booze.