If you happen to look in an attic and it looks like someone painted all the framing, you may have had mold remediation done.
After mold remediation is done, most remediators spray on a mold retardant to help prevent the mold from growing back.
A word of caution though, this is not always mold remediation work. Sometimes it is fire/smoke remediation which is an entirely different problem. Be sure to get proper documentation from the sellers as to what happened.
Dave Graham, Tempest Home Inspection. Calgary Alberta