Years ago I used to use a bit of earth scent or "cow in heat" cover ups. The urine left me with the rich scent of elk all the time I was hunting, so it was a bit motivating. lol I don't use any now. If they can smell the coverup, unless it is so thick that nothing else could be smelled, they'll still pick up the underlying odors. As far as the benefit of the scents as attractants... IDK. Attractants are the norm in trapping, but there is a concerted effort to not leave any scent at the set.