John, I would tell them that I if I see mold I will let you know about it! When I'm asked if I test for mold, I always ask the caller if they could see mold in the home or did it have a mold odor... Most of the time they say no! They just want to check and make sure, etc..... If they just want mold testing or insistent about testing, I send them to a local air quality guy who is also a home inspector, but he prefers to do air quality work. He knows building science well and helps folks to discover what is causing their problems. He does more than just testing for mold. I do offer VOC air testing for folks that do not have mold problems but other issues with their home. I use Prism labs Home Air Check testing system, I might average about 10 test per year. Really not a profit center but more of a service to give folks a direction for what their next step needs to be. Sometimes it is a simple as telling them that they need to get rid of the gas cans and cans of old paint in the garage!