Stem nematodes do severe damage to crops. As in, you wouldn't be harvesting herb. Unless legitimate tests were performed, I think it's just a "scape goat" (pertaining to herb).
Some strains look/smell/smoke just about the same, whether they are "perfect", or not. Some, in order to achieve that "magic" need to be nailed just right, some fall somewhere in the middle. My "Mystery" has to be pretty close to the "bullseye" to finish dense and deep/dark purple. Otherwise, you get green fluff (or something in the middle). Glue seems to have a sweet spot, icey faint pastel green, hints of purple/violet, loads of thick calyxes, strong sour cat piss fuel nose (undertones of earthy nutty chocolate coffee). Missing the mark leaves it darker, less icey, fewer calyxes (or none at all), and the nose doesn't develop beyond the earthy nutty chocolate coffee into the "pungent funk" (in my experience, the "sour cat piss fuel" is the nose it graduates to).
I haven't experienced dud branches or plants.