I work in a brutally competitive industry, with a very legitimate and always top-ranking site. We're constantly getting negative SEO attacks; I clean up about 1,000 links every month and add them to the disavow. We've never built any links (yes, seriously) other than PR. Last week we got a manual penalty for unnatural links, none of which we built. I again went through the link profile and disavowed. How long does it take utnil google reinstates the site? Losing tons of $ every day.