Yea Im gonna have to go with the Aints. I mean seriously, when your fans were the ones who started the whole paper bag over the head thing, its pretty bad. When they write AINTS on the front of those bags, its worse. Therefore it has to be the Aints with the Bungles a close second.
The Bungles are a complete disgrace. Even an elite QB like Palmer cant have steady success there.
But aside from them it has to be....
The Bills - One mini run of success where they actually turned out as complete failures losing 4 straight bowls. Best player in team history murdered two people. The team was terrible for about 20 years and is getting back there now. Plus they play in Buffalo
The Jets - One moment where Broadway Joe pulls one out of his ***. Outside of that they are perinial losers. Will probably never sniff the bowl again. Dont even have their own home stadium.
The Patriots - The only real success this franchise has had has been recent and resulted from cheating. Got lucky and pulled the 2nd best QB in league history out of the 6th round. The coach didnt even realize what he had until injury forced out the player above him on the depth chart. A nice dynasty put together with cheating and dumb luck. Outside of that the franchise consistantly failed and was remembered for losing on the most lopsided Super Bowls ever to a flashy juggernaugt in 85.
The Browns - The mistake by the lake. Enough said.
The others mentioned by Dlockz fill out the list, Lions, Cards, Yucs.