I would look into some of the chemistry as well that's out there. I myself have done quite a few commerical gigs in 2011. In some really bad cases I was able to make dramatic improvements to the overall appearance of the flooring. But in all reality there's simply some things you can't make "look new". I have made it very clear to these customers that we are not the company you're looking for if you want "brand new - day 1" results.
Keep in mind this was machine shops, slaughter houses, and other nasties. The rest were normal and easily cleaned aside of bad traffic areas that were neglected for several years.