So, you see a black spot on your sheetrock ceiling, what to do?  Well, you may very well have a water intrusion issue.  Pictured here is apparent mold growth on a sheetrock ceiling which, when probed with my moisture meter, revealed underlying saturation within the ceiling cavity above.  The likely contributing factor was a roof leak for which I recommended further evaluation, remediation and repair by a qualified contractor.  There is the possibility of underlying damage and mold growth not visible until the sheetrock is removed.  This was discovered at an Orcas Island home inspection in the San Juan Islands.