I've often thought about doing something like this for comments. I think it would work.
The hard part is getting the initial corpora of stupid and non-stupid text. Stupid writing is harder to recognize than spam. It might work to use sites as proxies.
Another related filter that might be worth trying to build would be one for recognizing trolls. It would be easy to collect the bad corpus for this filter, because the design of most forums makes it easy to see all the comments by a particular user, e.g.
The hard part is getting the initial corpora of stupid and non-stupid text. Stupid writing is harder to recognize than spam. It might work to use sites as proxies.
Another related filter that might be worth trying to build would be one for recognizing trolls. It would be easy to collect the bad corpus for this filter, because the design of most forums makes it easy to see all the comments by a particular user, e.g.
http://reddit.com/user/qwe1234/