Adapted from a comment thread:
If you decide in advance that the truth is always in the middle, it makes your life easier, but it cripples you with a jellified inability to respond effectively whenever one side or the other happens to be right.
Likewise, if you decide that they’re all crooks, you become incapable of spotting crooks.
The Republicans have learned to game the moderate voters by noisily claiming that liberals are really dangerous radicals, that moderates are really liberals, and that the conservatives are the real moderates.
Since one category of moderate voter is dumb as a stump, this strategy works far too often. I know that you can’t win by running against the voters, but — bless their little hearts — some of them are really hard to talk to.