I clean my mirror like this.
http://www.wwnorton.com/astro21/sandt/optics.html
I cleaned up a scope that was donated to our club the same way. That scope had been stored open in a garage for several years. Lots of dust, car exhaust and cat hair on the mirror. An hour of soaking in warm soapy water and a ton of cotton balls eventually brought it back to like new condition.