&gt;&gt;Advertising to someone who you have reason to believe is going to buy your product is much more effective than advertising to an unknown person.<p>Totally depends on the product and the person you are marketing to. Marketing hammers to carpenters makes sense: they use many different types, and presumably go through them quickly. Marketing faucets to regular folks is a dumb thing to do. A faucet is something you buy once in a blue moon.