Instead they are a little more of a grey area, but they're the foundation on which sites like Pinterest, Facebook, and YouTube stake their liability for your use of their services. The biggest (i.e., most money-making) issue that keeps cropping up is liabilty for copyright infringement.
For a few interesting articles on the headaches Pinterest has had related to copyright and its TOU, check out the following:
- Pinterest Hires Away A Google Attorney To Start Its Own Legal Department
- A Lawyer Who Is Also A Photographer Just Deleted All Her Pinterest Boards Out Of Fear
- Legal Concerns Around Pinterest: Advice from a Social Media Attorney