Affiliate marketing, if done professionally, definitely requires own websites for each product. The websites or mini-websites must have some content related to the product you are selling as an affiliate.

Of course, you can have a one-page sales letter and get your job done. But sales letters are not ranked in Google pages. Because they are merely sales pitches.

Imagine, you have a mini-website related to the product with at least 10-30 pages of contents. In this case, you will attract Google's natural organic search. You get free exposure in the search engine and free targeted traffic to your sites. You can lead the visitors to your sales page from every page of your content. Don't you think there will be some additional sales from these people?

Okay, since you have good content on the site, should you take advantage of AdSense program in your websites? Not a good idea. Why would you like to lose your visitors for the sake of a few pennies per click? AdSense ads actually distracts people and diverts attention from the original topic.

However, you can use AdSense on specially created websites.

Purchase some separate generic domain names and buy some AdSense sites and host them. Since you have a hosting account anyway, it doesn't cost you anything. Simply upload the websites with your AdSense code. Since the articles are keyword rich in AdSense websites, it will attract search engine organic traffic. People who read the content out of curiosity are also likely to click the AdSense ads. Though you will be making only a few pennies per day, with hundreds of such sites you can manage to earn thousands of dollars.

Here, the content has to be unique in order to qualify with Google. The best way to go about is to hire writers to rewrite the articles and add more content. Usually, when you buy a ready-made AdSense website for cheap, it wont be unique. Google may ignore your site if it senses duplicate content.

So setting up AdSense websites is not overnight job. It has to be spread out through out the year. You should upload only a few sites per week. Not in hundreds. That may give rise to spam.

AdSense can earn you good money with proper planning and promotion of the websites. You may also include your affiliate links in your AdSense sites. These links will become another source of income.