I'm curious, normally when I'm fishing a fluke, I look at it as a reaction bite. In other words, I don't think line visibility or scent matters too much in that context.
Has anyone performed a deet test on something like a plastic worm or Senko? Deadstick style?
I think even Hannon's gas test was on a moving bait, like a swimming worm or Rapala maybe? I can't recall exactly.
I can say for sure, that I personally do much better on non-reaction (slow or non-moving) baits, with clean hands: no deet, sunscreen, no gas, especially no human scent to the extent that I can control it, I even wear rubber gloves sometimes when fishing slow baits and live bait...
I don't use scent (attractant) all of the time, but I do put it on if I feel like I should be catching fish on non-reaction baits and I'm not, or of they aren't holding the bait well, and sometimes it seems to help.
I think, if you're going finesse, you're fishing for inactive fish and you need to go all in. Don't give them a reason not to pick it up if you can help it.
If you're power (reaction) fishing, and you have the conditions right for that(wind, low light, current, stained water, etc...), you can get away with a lot more and scent is useless.
Having said all of that, I'm pretty sure WD40 is a known fish attractant too, so there's that