Give Your Testimonials More Credibility
http://www.excessvoice.com/article106.htm

Usborne, Nick
Excess Voice
2006

Abstract:

I think that the people who give the testimonials do so for the additional exposure they receive for their own names, sites and businesses. I also think they do some mutual back-scratching, and hype each other's products and services. In other words, the testimonials are just additional sales text. They have no credibility as outside, third-party endorsements.