If you don't have enough ads on your pages, you won't be able to monetize your site enough to make it profitable. But the opposite could be just as bad—too many ads on a page will take away from the user experience, make pages hard to read, and drive your audience away. Really, nobody likes an ad whore. Strike a good balance between your content and ads so that the content is easy to read and absorb, and there are enough ads to pay the bills plus make a profit, but not so many that they become the focal point of your site and overwhelm the layout.