It's certainly an interesting topic. The guy that invented Gulp! also said that gasoline did not affect fish. I've also seen where people get one drop on their fingers and dont get a bite after. As far as the water solible vs oil based, shad are an oily fish. Skipjack, which big blue cat chasers prefer, are oily. Lots of saltwater fish like menhaden are oily. Does that make them more appetizing to predator fish, I dont know, but they like them. But I'll say I caught my pb lm in January from the bank on a rapala shad rap with no scent added, it was around 8 lbs if i had to guess. But without a doubt a fish can inhale and spit a lure in the blink of an eye, so if it gives me an extra split second for a good strike I think it's worth it