Been a long while since we had any sort of discussion here on scenting plastic baits: whether it works or not. As long as we're in the winter doldrums lets kick some thought around.
I'll start by saying I have some specific thoughts on whether scent will work or not based on whether the scent is oil or water based or even if its based on oil will the oil mix with water in the short term [emulsify]. My feelings are that fish live in water and that their scent sensory organs may not be able to "smell" things oil based. But I am open to the idea that beyond the smell itself, chemically they may be able to pick up scent. Again personally, I have used cod-liver-oil as a scent for years and have noticed that at times it makes a significant difference. This oil is one that is totally organic so my oil theory gets a hole punched in it because I think the organic compounds are ones that fish can pick up on as a "food" smell.
I am a huge advocate of Gulp and PowerBait products, especially the Gulp juice. Neither of these is organic...totally synthesized. But they both work in their own times....like the cod-liver-oil. Power baits seems to work even when a bait is cut off or broken so it is more than apparent that the compound is cooked into the bait. Gulp appears to be a surface product, hence it's coming in the juice. Its obvious to me that the chemicals found in these product likely mimic pheromones that fish react to causing a better likelihood of the fish hitting it.
I am also a huge advocate of using anise essential oil mixed in regular worm oil as a cover scent in the plastics I make. I use it topically, not cooked in. The pictured one ounce bottle will make a potent scent in one gallon of worm oil. I ordered two of these bottles ten years ago and this one is still un-opened and the other still half full. One single drop of this mix goes into each bag of baits. I know it hides a world of scent sins like gasoline and smoke but I swear it also acts to get fish to hit better.

I have used a couple of the Upper Hand Scents that is available thru Do-It's store and have tried cooking it in and as a bagging scent and I have played with cooking it into the plastic. I think cooking it in changes its smell and I cannot recall ever getting bit when using a bait with it cooked in, so I no longer use it in that way. I feel that it works to some degree as a bagging or topical scent and on certain days I feel it helps with hits. Its oil based with what I assume are organic compounds so there has to be something that fish can sense. Like the Gulp and PowerBait where I think Berkley has been able to chemically replicate scents or pheromones it goes well beyond smell and is likely something so small it would boggle our minds. But it's there.
I'm curious what products others of you use for scenting the soft plastics. Do you cook it in, and if so, why? What particular scent gets the most reaction for you. Do you bag baits using scent and, if so, which products? Lets kick this around and see what ya'll think or do.