In short, for products where bikini-clad babes represent an appropriate marketing strategy (I’ll let you be the judge of what those product categories are!), the place to put them is at the point of sale. I’d use them in ads more distant from the point of purchase, like television commercials or print ads, only if they are an integral and long-running element of the brand strategy (e.g., Hooters restaurants).
P.S. (this post has received more visits by far than any other)