I suppose "decent" is one of perspective. I know one of my most intelligent followers, who is also pretty Conservative, would probably find several of candidates decent; I won't posit which ones but would guess it wouldn't be Romny or Huntsman, not that he doesn't consider them decent, but they don't reflect his views strongly enough. Me, on the other hand, consider Romney the only, of the ones I have studied, I think would make a reasonable President (my choice is Obama) and actually has a chance of winning once he can stop lying (that is what politicians do, you see) about what he truly believes in order to get nominated; independents are still upset with Obama and may not go back to him and if a moderate Conservative is running, the Liberal Democrats may not vote.
Back to your question. The rest of the field are not decent in your view, and in mine, because they are so far to the right. But, they are decent, popular, nominatable, and electable because they strike a chord with the right-wing element of the Conservative wing of the Republican Party. To the rest of us, they are decent cadidates meaning they are not electable in a general election, however, unless the economy has tanked again. For most of them, they are so far to the right that even if unemployment and growth remains where it is, I feel it is Obama's election to lose.