Mold smell in house

[Bienes Raices]

I'm looking at an REO that seems to be a decent deal. However there is a mold smell in the house. It's not overwhelming, but it is there, and I don't know what the source is. (There is no visible mold that I can see). The flooring was removed in two rooms--don't know if the bank did that before putting house on market or if the flooring could have been moldy. I went to the house twice and the first time there was some kind of loud portable device running in there--maybe a de-humidifier?

Anyway, if my offer is accepted I'll have a full inspection done, including mold test. But as for the smell, is there a good way to get rid of that permanently, once the source of the mold has been cured? I'm concerned that the odor could linger and drive away potential tenants. Thanks.