In general things have to release molecules of some substance for us to smell. From break down, terpines (?) for any cannabis extract, residual chemicals or other things used in making/extracting the substance. If someone gets DMT that smells of acetone it's because the "manufacturers" didnt properly finish the process.
Pure 100% pharma grade heroin would have no smell. That's from some DEA agent off some drug documentary. The dogs smell other things attached to it such as opium transfer, chemicals or something else. Some drug dogs have been shown to alert to plastic bags since they release small amounts of . . . "volatile oxidizing chemicals"? Real new car smell. The smell of all the various products releasing "VOC"s
My grandpa told me never trust a vagina that doesnt smell. There's a reasons she is keeping it so clean. Haha. . . .still doesnt mean it isnt potent tho. In Germany the red light lady was fentanyl compared to heroin. . . . . just saying . . . .haha