They were knowledgable and honest. We had initially just hired them for a deep clean of our ducts, but Steven discovered that there was basically no dust. Instead he found mold in our AC unit and inquired whether we suffered from respiratory problems. (We have been, as a matter of fact.) He used nontoxic/natural products to treat our vents. We paid $394 for the whole service, which is very reasonable considering that it includes a warranty and additional follow up treatments.