Science has a built in mechanism by which it can root out false or baseless assertions put forth by - well by anyone - but especially by members of the scientific community.
At it's core, science demands that ideas be challenged with empirical evidence and logical reasoning. For practitioners (whether career scientists or otherwise) there is then an assumed responsibility to ensure those core demands are properly put into practice. This results in a kind of social norm among scientists that they are critical of one another, and that they hold themselves and their peers to the highest standards of scientific inquiry. The result? If it doesn't pass muster, it won't get past too many people before someone cries foul.
Over at the blog Why Evolution is True there's a nice, recent example where you can see this process in action.