D.M.
This is going to sound so simple it's ridiculous, but it really does work. I used to use the Swifter and the Orange Glo stuff and it never really cleaned it well. Just use hot water and add some vinegar to it. I usually fill a 3 gallon bucket about 1/2 full and add roughly 2-3 T of vinegar. It takes a couple of weeks, but you'll be amazed at the shine and the dirt you'll get up.