Most of them are usually there in January and July though. To the poster who asked if they're that bad, imagine 100 teenagers with only 1-2 adults to corral them. They are like a swarm of locusts devouring everything in their path. If you are in line for a ride, one will slowly ease past you and once he gets to the front of the line, will let out an ear piercing whistle. Suddenly 200 teenagers are knocking down everyone in their path to get to their friend. If you are waiting for a bus, there will be one kid waiting and when the bus arrives, again you will hear the ear piercing whistle and suddenly 100 kids arrive from seemingly no where to cut line and fill the bus. Once on the bus, they sing at the top of their voices all the way to the park and then scream all the way back to the resort that night, while your kids are trying to sleep. According to the CMs they literally destroy the rooms they are in. They will have their adult tour leader get them fast passes and if you happen to be stuck behind him, imagine waiting until he puts 100 room keys into the fast pass machine. I swear the only thing those tour leaders do is go from fast pass machine to fast pass machine, while their kids cause havoc. In Epcot once, I saw a swarm of them knock down a little girl, never stopped, just turned to look at her as she cried,and then started laughing. I also saw a very dangerous situation with them at DTD that same trip. A bus pulled up and they knocked a family away from the door of the bus and in the process a little boy got sperated from his parents and got knocked down and literally round up almost under the bus in front of the tire. My neighbor at the time was Brazillian and I was talking to him about them after I returned that trip. He said it is a coming of age thing for the families to send the teens to WDW the year they turn 16 y/o. He also said the families have no idea how they act up here and that normally the Brazillians are very respectful (if funloving) people and that their families would be horrified if they knew. However, what can you expect when you get 100+ excited teens together with basically no supervision? Oh yes, if anyone says anthing to them, they pull the 'no English' routine, however, according to my ex neighbor these kids come from very wealthy families and are fluent in at least Portuguese, Spanish, and English. To be fair though, I have seen some of them give up their bus seats to mothers with young children. It's just that there are so many of them, they are sooo loud, and they seem to have no concept of what a line is. Also they travel in humongous groups, always chanting.
There are those who say they are no worse than the POP Warner kids, except the POP Warner kids have more adults supervising them.