g1smd - 10:20 pm on Jan 15, 2013 (gmt 0)
will disallow crawling of URLs with a % in.
However, as stated above, that's the right answer to the wrong question.
If the requests are met with a 404 or 410 response then there is nothing further to do.
If your server is returning '200 OK' then you have a bigger problem to fix.