I guess different folks have different experiences. We were there during Pop Warner last year (and in the past also) and didn't really notice them much. We stayed at BWI, so it didn't make any difference there. We saw some groups at Epcot and they weren't badly behaved at all. At the other parks, we only saw a few, but again, they were not a problem. In the past, I have seen groups breaking into cheers, but not this time.