We use the information we collect to provide the Service to you. We commit to showing you content that’s relevant, interesting and personal to you. In order to do that, it’s necessary for us to use your information to: [...]This is not 'necessary' - if you're trying to make it 'relevant', 'interesting' and 'personal' you should respect the wishes of the many users who can find relevant interesting personal stuff themselves and do not want you to recommend stuff to them (and have told you so, repeatedly).
[...] It is also fundamental to the nature of the Service we provide. In short, it’s necessary for us to do these things in order to make the Service relevant, interesting and personal to you like we promised, and it’s in both of our interests for us to do that.
- Recommend Pins, boards, topics or categories you might like based on your activity on Pinterest. For example, if we see you’re into cooking, we may suggest food-related Pins, boards or people that we think you might like or show you food-related ads.
[Edit - Pinterest is not as bad as I thought - here's how.]