Filthy wood floors that don't come clean usually result from one of two things: The surface finish (Swedish oil, wax, varnish, polyurethane, etc.) has not been stripped in too long a period, or the surface finish is missing entirely.

Test an inconspicuous area with a few drops of water--if it soaks into the wood, the finish is gone. If the water turns white, there is wax on the surface. If the droplets bead up, the floor has probably been oiled or coated with polyurethane or varnish.

The best way to prevent floor from getting this dirty in the first place is to use a quality floor cleaner on a regular basis. It's important to choose a cleaner that is gentle enough to be used regularly without damaging the finish but strong enough to remove dirt and stains.

Use a commercial wood floor cleaner to strip away oil or wax finishes that have become discolored with ground-in grime. Dark stains in the wood may have to be sanded out using a professional floor sander.

Why we like it: • Gentle on surface but cleans effectively * For both real wood and laminates • Non-toxic--safe around kids and pets

Surface finishes like varnish and urethanes sometimes can be revived by buffing with steel wool or a special pad made for this (rental stores have the machines and replacement pads). If that works, recoat the floor with the same type of finish. If the dirt doesn't come out, the floor may have to be sanded to remove the topcoat and then refinished.