it might be a good idea to have a mechanism to move the user on to the default of alll.
If by "default of all" you mean removing the keyword "scarf", that does not work:
http://fineartamerica.com/art/all/
Neither does going back to the root of "art":
http://fineartamerica.com/art/
I think the advice of improving bad link trapping and sending the user back to a default page or a 404 not found page is good advice.
It appears FAA is aware of it, and if judged important enough, it will be forwarded to programming.
closing now.
Edit: actually, I just noticed the page is actually titled "page not found." It appears it was not properly sent to the default 404 page not found template. Easy enough to fix.