Should I buy a cheap home with mold as an investment?

Mold is not an easy fix, and you have to be willing to gut the structure (partially or completely) for complete remediation of the mold problem.
Since this “Cheap” house is an investment, be prepared to carry the house for 3–6 months for the mold remediation, sheet-rocking, painting, and more (duct cleaning, additional venting, replacing paneling/cabinets/doors to eliminate mold, etc. Look hard at the numbers, get estimates before jumping in, and be prepared to accommodate the “worst-case scenario”, if the mold is more extensive and takes more time and money to remedy.
Mold Money: How to Save Thousands of Dollars on Mold Redmediation and Make Sure the Mold Is Gone
Mold Money: How to Save Thousands of Dollars on Mold Redmediation and Make Sure the Mold Is Gone
Have a certified mold inspector check the health of the house after repairs, and carry insurance for any liability – mold makes people sick; you don’t want to be sued over it if you did a quick or sloppy job clearing it up.

 

Best of luck!