According to a recent study conducted by Princeton University's Arunesh Mathur, Arvind Narayanan, and Marshini Chetty, the majority of YouTube and Pinterest posts containing sponsored content don't provide any indication of that fact. That's not to say the findings, which took into account around 500,000 YouTube videos and 2.1 million Pinterest pins, are altogether unusual. In fact, based on the past five years of data, Pinterest users appear to be getting better at disclosing that information while YouTube has maintained an average. Moreover, the majority of posts on either is not affiliated content at all - less than a percent of those that were studied. However, the aptly titled "An Empirical Study of Affiliate Marketing Disclosures on YouTube and Pinterest," does show that 90-percent of affiliated content is not marked as such.
For YouTube, only around 7.02-percent let on that a video or video description contains affiliate links while only 1.82-percent follow FTC guidelines to explain what affiliations are present. Meanwhile, just under 2.5-percent relay the fact that their YouTube channel is receiving support from a sponsor. That adds up to around 8.99-percent of affiliated content being disclosed on YouTube in 2017, compared to a five-year mean average of 10.32-percent. Pinterest, as mentioned above, seems to be doing a bit better over that same period, with a total disclosure rate of around 11.2-percent. That's above the site's five-year mean average of 2.626-percent. Its explanation disclosure rate is also above YouTube's - at 2.43-percent - although the rate of affiliate link disclosure is lower at 4.6-percent. So Pinterest does better overall and with disclosing the FTC's recommended explanation of affiliation. That means that, on average, Pinterest users publishing sponsored content do a better job of explaining how they get paid for content they are posting about.
Of course, not all categories on either platform are equally likely to contain sponsored content. On YouTube, the top three categories for sponsored or affiliated content are its How-to & Style category, as well as Gaming and Entertainment categories. Of the videos studied, the first category saw a prevalence of that type of content of around 23.68-percent while only around 24-percent of those featured a disclosure. For Gaming, the number drops to 11.22-percent containing the content and 12.8-percent reporting. Last, the Entertainment category saw a similar number of videos with affiliate content but only around a 10-percent disclosure rate. Perhaps surprisingly, the "Animals" category tops Pinterest for sponsored content with 60.67-percent of studied content in the category containing affiliated content and 36.6-percent disclosing that fact. That's followed by the Food & Drink and Health & Fitness categories, which saw affiliated content in 14-percent and 12.76-percent of posts, respectively. Approximately 10.3-percent of posts in the former category had disclosures, while the latter fell in at around 11-percent.