Netflix has trouble policing advertising affiliates

Netflix has a strict policy of not affiliating with advertisers who install adware or spyware, but even with the best intentions, it is extremely difficult for them to control the actions of all their affiliates.

From Center for Democracy & Technology's report on "How Advertising Dollars Encourage Nuisance and Harmful Adware and What Can be Done to Reverse the Trend"

Netflix is one example of a company we contacted that already had an advertising policy in place to address adware. Netflix expressed concern that its ads are appearing via 180solutions software since the Netflix policy explicitly prohibits the display of ads through any adware or spyware program. A Netflix representative investigated the situation and assured CDT that the example found was unique and random, and that the behavior that caused the ad to be served by 180solutions software had ceased. However, within hours of receiving this notification, CDT found three more examples of Netflix ads generated by adware programs. It is important to note that Netflix is one of the largest online advertisers that CDT contacted. To CDT, this illustrates the difficulty that large companies have in enforcing their policies given the current online advertising environment, and the complex web of relationships involved with placing ads. Some companies have instituted detailed auditing processes to address this concern, but more emphasis must be placed throughout the advertising industry on policing advertising networks and dealing only with trustworthy affiliates.