If you really feel a need to disinfect, see the instructions on a bottle of laundry bleach; they'll suggest an appropriate dilution for that purpose.
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I'd also add my standard comment: If you're trying to get rid of organic odors, the enzyme products used to eliminate pet odor are pretty cheap, and as long as you get things dried out again so mold doesn't start growing they're quite effective. The one I've used is Odor Mute (sold as a stable powder, mix required amounts with water as needed), but there are (or were) a fair number of other brands.Of course if the basement stays damp, it's also going to stay musty-smelling. Consider a dehumidifier.
If the basement is thoroughly trashed, you'll need to do both what Kiteman and Ork suggested, one following the other, and I'd even let the basement air out afterwards and then nuke it with concentrated vinegar (and then air it out again).While the basic dirt and grime can be removed by scrubbing, bacteria mold, etc are going to be a bit tougher to purge. And while the Hydrocholoric acid in bleach is pretty good, it is no where near as effective as acetic acid (vinegar) is killing organisms.Since you're going to be working in a basement, I'd recommend opening all the windows and limit the time you spend when working in either a bleach or vinegar laden environment. I have to periodically treat my very old basement for mold and generally evacuate the house for the day after doing it. Maybe I'm just sensitive, but prolonged exposure to the fumes from either can be pretty bad for you.
If it's painted, just use ordinary hot soapy water and a tough cloth.