No recognized federal, state, or local health agency has created a standard for acceptable and unacceptable levels of mold inside a building. Consistent mold growth can be indicative of moisture issues resulting from plumbing or other leaks in the home. Inspectors can address any active sources of moisture that may be a violation, but cannot address the presence of mold or require its removal. It is up to residents and/or property owners to clean up existing mold colonies.
For resources on mold remediation, visit the EPA website linked below.