FTC Guides for using testimonials
Some time ago the Federal Trade Commission (FTC) adopted a set of Guides Concerning the Use of Endorsements and Testimonials in Advertising.
The guidelines talk about celebrity endorsements, blogging endorsements, use of testimonials in general (including non-celebrities), and sponsored testing.
On the FTC website is a pdf document that you can read about it (81 pages), see the link at the bottom of this article. I’ve pulled out and summarized some components here that I think are of interest to advertisers and ad creators.