We're planning to carpet the basement in our 100-year-old house, which presently has a painted concrete floor. The floor happens to be quite uneven and seems to have been designed to channel water into a now-plugged drain. No water issues in the basement since we've lived here, so this appears to be an obsolete feature due to likely corrected basement water problems.
Several contractors visited and told us that all we need to do is lay down the carpet and padding on top of a vapor barrier, skipping subfloor construction. They said they'd even out (but not level) the flooring by using a form of leveling compound.
I'm not particularly concerned about the "cold floor" issue, but I am of course concerned about the possibility of moisture buildup leading to mold or musty smells. It's certainly appealing to skip the whole subfloor given that it would save the need to level the floor, save money, and we'd retain important headroom.
However, I'm concerned about the moisture implications. A couple of the contractors seemed confident that the painted floor stops moisture from rising through. If it's as simple as just painting the floor, why do I read about so many people recommending insulation and a full subfloor?