I think the most dramatic evidence that I saw was a movie a few years back involving underwater cameras which viewed two flasher/fly rigs trolled behind a boat. The fly that was soaked in bilge water/oil/gunk out fished the "clean" fly consistently.

I later experimented with jigs, going so far as to dunk them in my fuel mix....guess what, they worked great. So if your conclusions are drawn solely on someone else's "always done it this way", maybe your own experiment will lead you to a different conclusion. Or not.

Cleanliness may be next to Godliness, but I doubt seriously that it catches more fish.

Personally, I like the "Fish like the bubbles."