We see 10-12 "grow operations" every week in this area. It is legal to grow. I have seen 40' x 60' pole barns with 4" foam insulation (100%) and enough lights for downtown Denver! Also, anecdotally, seen dozens of potential buyers walk when they see the evidence of past use of the building or room. I am not passing judgment, just wondering why an inspector would or would not mention it? I am working on one of my rental houses that has been used for growing pot. There is enough scrap/residue for an enjoyable few days. Do I just vacuum it up? or should I have the ductwork cleaned?