NHL-Maples Leafs fans. They are the ultimate losers, supporting a team that takes their money and does not put out a viable product.
NBA-Lakers. I hate to say it but most of them are fairweather fans who only support the team when they are winning. I used to cheer for them in the days of Magic and even was a fan during the days of Van Exel and Eddie Jones but I know that is not the majority of their fanbase.
NFL-(tie)Jets,Eagles,Bills. All northern climate teams whose fans have one thing in common. They are all slobs. These teams never win anything, never entertain the fans and from watching these teams play at their home stadiums their fans just seem to be the lowest percentile of humanity.
MLB-Cubs. See Toronto Maple Leafs, I believe they are truly cursed.