Not all BO and sweat are made alike, and if the sweat isn't fresh (and, for example, dries on clothes that aren't removed or, worse, reworn), it can smell sour. But good BO can be so good. Your girlfriend is hardly alone. In fact, there's a gay party in New York called Pheromone that caters to guys who want to stick their noses in each other's pits.
The implication of the ads is clear: You stink. Not just your armpits-your entire body, head to toe, absolutely reeks. In your default state, you're basically a gallon of milk accidentally left in a hot car. Never mind that an overwhelming percentage of the sweat glands on the human body don't actually produce body odor. According to the now-ubiquitous advertisements, whole-body deodorant is meant to be sprayed everywhere: