There should be a one month probabation period, where newbies can only reply to threads.
There are so many great ideas that come out on FR. And this is one of them. I agree with this idea.
Now THAT is a good idea. I'd also suggest that they be required to respond 25 times before being allowed to creat a new thread. That'll help with sleepers. Granted they could just do a bunch of bumps, but one look at their post history will out them quickly.