I had a lot of fun writing that article but must confess, I have never used attractant for trout. Given the nature of trout waters, the effectiveness of attractant to lure fish would undoubtedly be significantly reduced.
On the other hand, I still believe the following (from the article) does lend creedence to the need for covering human or petroleum scents.
What replaced nature is nylon based threads, chemically processed fiber dubbing and chenille, plastic and metal tinsel and hair, rubber and silicone l egs, foam, wire, glues and varnishes. None of these smell like fish food and many contain smells that repel bass and bluegill. Gasoline is reputed to be the most repulsive, followed closely by solvents — like those found in glue and head cement. Of course there is the amino acid L-Serine, found in humans and immediately identifiable as a bad thing by bluegill and bass. Human skin emits L-Serine odor and can (inevitably will) transfer this to a modern fly. The result is, when bad things combine, the fly might actually repel fish.
For warmwater fishing, I find attractants can make a significant difference in catching success. Most recently I had panfish refuse a known producer fly i tied and finished with CA glue. After putting on a small spray of garlic attractant I caught three large male bluegill in the same spot that refused to produce a bite. Because I like catching more than fishing (see my other articles) that's the kind of result I like to see.