I am a Tidus hater. And here's my reasoning.
1) How is he such a good fighter? He's a blitzball player -- that doesn't seem to make anyone particularly strong or battle savvy. He has a sword. Good for him.
2) His outfit. The horrors!
3) His voice actor. Not his fault, but I could not listen to him! It was abysmal.
4) He's portrayed as whiny through most of the game. No other FF main character came across as a crybaby before -- it throws me off. It was so unappealing.
5) He looks like Meg Ryan. Kidding.
But seriously.