Affiliate marketing currently lacks industry standards for training and certification. There are some training courses and seminars that result in certifications; however, the acceptance of such certifications is mostly due to the reputation of the individual or company issuing the certification. Affiliate marketing is not commonly taught in universities, and only a few college instructors work with Internet marketers to introduce the subject to students majoring in marketing.
Since the emergence of affiliate marketing, there has been little control over affiliate activity. Unscrupulous affiliates have used spam, false advertising, forced clicks (to get tracking cookies set on users' computers), adware, and other methods to drive traffic to their sponsors. Although many affiliate programs have terms of service that contain rules against spam, this marketing method has historically proven to attract abuse from spammers.
In the case of cost per mille/click, the publisher is not concerned about whether a visitor is a member of the audience that the advertiser tries to attract and is able to convert, because at this point the publisher has already earned his commission. This leaves the greater, and, in case of cost per mille, the full risk and loss (if the visitor cannot be converted) to the advertiser.
Websites consisting mostly of affiliate links have previously held a negative reputation for underdelivering quality content. In 2005 there were active changes made by Google, where certain websites were labeled as "thin affiliates". Such websites were either removed from Google's index or were relocated within the results page (i.e., moved from the top-most results to a lower position). To avoid this categorization, affiliate marketer webmasters must create quality content on their websites that distinguishes their work from the work of spammers or banner farms, which only contain links leading to merchant sites.