I don't have a lot of experience with clickbank.com but still I make decent money every month. It works out better for me than using regular ads like for example, bidadvertiser, adbrite…. It works out better than AdSense.
With AdSense I can make up to hundred dollars per month per site with high traffic at least 500 unique visitors per day. With clickbank.com I can make somewhere around $200 – $300. The good thing is that the owner of the products, already wrote the landing page, has already spent time usually to test the ad. You can easily just place the ad on your website and earn money on autopilot.
Usually I check which are the ads that convert the most and are the most successful and used by other publishers. Then you just select the ad that is close to your niche and make few banners in Photoshop for each ad. You can do that in 5 min. with Photoshop. Then you link each ad to the landing page of a person who sells the product. Done deal. This is easy money on an auto pilot.
Clickbank.com only works if you have high-traffic sites, but that is a rule for most all advertising. Then I can just log in and check your stats. What I don't like is that they don't use PayPal payment. That is a big minus.
What I don't like also is that you have to share the commission with other people. Even though the commission is very high, sometimes up to 70%, you still have to share your profit. And in worst-case scenario, the owner can double opt in the user and use him for future sales. And sometimes another publisher steals your web cookie, because he sells or advertises the same product but the buyer visits his website after yours, and you lose the sale completely.
The best way is to create a product yourself, create similar landing page and take the whole commission. However, for quick cash on autopilot this is a good way to earn money online. And you don't have any costs or investments. This can save you time if you rather live on the beach and relax like I do instead of working 10 hours per day.
What you can also do is use the program called heat map where you can clearly see where your visitors clicked the most. It can be the header area, top left corner, top right corner, right or left side of the website. Then you can place the ads accordingly.