Well, this is an interesting question, so I'll give it an interesting answer...
First off, if we hate the person who starts off strong, it's because it's quite possibly the stupidest thing you can do in the game. Why? Because you start off with an enormous target on your back because you're deemed as a 'strong' player. Even Jase said that he originally planned on throwing the competition, and laying low for a while. Domination in BB is never a good thing, because if you dominate long enough to be deemed a threat, then as soon as you don't win, you're up on the block and gone.
However, the reason that I strongly dislike Scott and Jase is because they're annoying. I mean, Scott's always talking about how 'wonderful' they are and 'how much power they have', but he doesn't realize that, after each round, it can all change. They aren't guarenteed a spot in the final 4 - they still have to work for it. Plus, both Jase and Scott remind me of Zach from P-Ho, mainly because they have the headbands (good god, the headbands), they think that they are oh-so-pretty, and must maintain their manly phisique at all times, and they think that they're smart, when they really aren't. (Ok, so Jase is a little smarter than Scott and Zach, but those two are a little bit dumber than a piece of fruit).
So, those are the two reasons I think that most people don't like Scott and Jase. They're playing the game with force, not strategy, and they're annoying a-holes.