Thomas Cook tourists from England. Drunk, loud, red sunburnt skin, loud, messy, loud, zero manners, loud. An absolute menace at every holiday destination. Almost as bad as rich Russians who think everything is theirs to damage and everybody is there to serve them only.
As somebody who lives in Central Europe (which, to most Brits, is apparently the same thing as Eastern Europe), I can fully attest to your observations. British tourists are incredibly uncultured and rude compared to pretty much all other tourists you see around here. Which is quite funny when you think about how, historically, they tended to portray themselves as more sophisticated than other folk*. Rich Russians are a menace, especially if they're anywhere near a car, but they have a niveau of behavior your average Brit could only dream of.
[*] I once even heard a group of them outright declaring that they're the "best" people in the Universe, and that "we've kicked these guys' arses every time we came here" (never mind that this country has never been at war with Britain). They then proceeded to threaten the nightclub owner (who threw them out of his club, hence the argument) to go to the British embasssy and "you'll see what happens". They were bloody serious too; I wish I could say this was an isolated incident, but these things happen practically all summer, every summer, if you live in a touristy city.