Robin Hanson, quite the contrarian himself, offers contrarians some advice:

On average, contrarian views are less accurate than standard views. Honest contrarians should admit this, that neutral outsiders should assign most contrarian views a lower probability than standard views, though perhaps a high enough probability to warrant further investigation. […]

He goes on to list a few common but inadequate contrarian defenses and offers critiques of each:

1. They Laughed At Galileo Too
2. Standard Experts Are Biased
3. We’ve More Detail Than Critics
4. Few Who Study Us Disagree

Overcoming Bias: Contrarian Excuses