I've been doing some work with UpperHand's CherryBomb scent. I've offered it two ways: cooked in and as an oil added to the package. The added scent is doing a better job of selling baits.
From the standpoint of preference on my part, adding the scent to the package is the clear deal. I don't end up with scraps or partial bowls that have an odor to them. A simple rinse in alcohol gets rid of the smell should persons not want to have it. If its cooked in its there to stay and offers no alternative. If a person is making baits for personal use and wants to cook the scent in, have at it. From a market standpoint, adding scent to the package just makes more sense.