There is gum chewing and there is obnoxious gum chewing. If you are a person who chews with your mouth open it is obnoxious gum chewing and so are the rest of the person's table manners. Dance or no dance...it's rude.
As to a guy chewing gum...I would rather that then those guys that have the white crust at the edge of their lips. When I see that I run.