When you're working up close at tables or cocktail receptions, it's always professional (as well as a good personal habit) to smell good. This includes both your breath and your body. To combat halitosis I developed a habit, when I was working on a weekly basis in several restaurants, to place a small handful of strong mints in a pocket. As the evening wore on I would pop a mint every so often and over the course of the night I maintained nice breath. It's now a habit that I continue for stand up and stage presentations because I am still interacting with clients and audience members before and after the show. The brand I currently buy is sugar-free Altoid Smalls. The one habit you don't want to develop is chewing gum to obtain fresh breath. If you chew gum when interacting with your client, my personal feeling is that you give off a unprofessional and an overall negative casual attitude toward your relationship with them. For obvious reasons this applies to chewing gum while performing as well.
Body odour from perspiration is another factor to contend with as a performer. Most of us sweat and some of us, at the very least, glisten from time to time. I have experienced two extremes as an audience member at more than one magic performance. There is the performer who overcompensates his fear of creating a stench by lathering himself up with enough cologne to kill a herd of rhinos at 20 paces. This is not a good alternative for body odour as many people deal with extreme allergies to perfumes, aftershave and cologne. I do not have allergies to perfumes but I do cringe and try to escape the overwhelming intoxication of someone who has overdone it.
At the other end of the spectrum there is the performer who is oblivious to his odour and perspires himself into a rank puddle on stage. Even from a distance this guy smells like a gym locker room full of aging wrestlers.
The main idea is not to be the guy who smells like he fell into a vat of Aqua Velva, or on the other hand smell like King Kong's crotch either.
Somewhere in between is the happy medium that your audiences will tolerate and appreciate.