While some Crossfitters can be annoying the majority of those I know are just normal people wanting to get into shape. Of course it may take a while for the transmogrification from normal enthusiast to full on nutbag to take place...
With that out of the way I have to say that the local Crossfit classes have recently become a class. As in just one class, not two. I spoke with a couple participants and they are tired. And SORE.
Anything can be bad for you if you overdo it. I think that's what's happening.