Cost per action/sale methods require that referred visitors do more than visit the advertiser's website before the affiliate receives a commission. The advertiser must convert that visitor first. It is in the best interest of the affiliate to send the most closely targeted traffic to the advertiser as possible to increase the chance of a conversion. The risk and loss are shared between the affiliate and the advertiser.
The best way to think about affiliate marketing is quality over quantity. There are a lot of small websites that will promote your product, but the key is finding a small number of partners that will deliver conversions. For example, an equity management services firm has over 20,000 affiliates in its system, but only about 25 affiliates generate 85 percent of revenue.
Affiliate marketing is often touted as a "get rich quick scheme" by shady sites offering pyramid schemes that promise quick cash for little effort. Make no mistake—successful affiliate marketers like Pat Flynn of Smart Passive Income put in a lot of effort toward building an audience and creating quality content that will bring in sustainable passive income. Expect to do a lot of legwork up front—but if you play your cards right, you can build a solid source of revenue over time.