Scent creates atmosphere and attracts attention. On the other hand, some people are allergic. Holiday music in a booth selling holiday items - what could be better to get shoppers in a festive mood. But, if there is live music being performed, and music in other booths, it might just sound noisy. Depends on the show, and the booth location.
Good lighting is essential.
If they can't see it, they won't buy it. There is a good chance you will lose that sale. And last but not least - Your personality.