Pay Per Click Stay on Topic

Since PPC ad networks target their ads primarily by topic, rather than geography or demographics, that makes these networks work better with niche topic websites than with sites that target their readers by geography or other demographics, such as gender, education, income or political affiliation.
For the system to work well for you, the PPC network's spiders must be able to determine a topic for each of your webpages and then must match keywords or phrases that advertisers have bid upon. That means the advantage goes to websites where each page covers a distinct and easily identifiable subject. So if you have a blog that covers a mishmash of topics on a single URL, you won't elicit the targeted ads that lead to high-paying clicks.
If you want to use PPC ad networks, organize your content to limit individual URLs to a specific topic. Break long blogs into individual entries. Archive old posts and stories by subject matter, not just by date and author. Stay active on discussion boards, keeping threads on topic and directing folks to more relevant pages should they stray toward other subjects. Use keywords in headlines, decks and URLs whenever possible. And spell out keywords, phrases and proper names on first reference, rather than using acronyms throughout the piece. (See, old fashioned copy editing rules *can* help you make money!)