Do you really believe that those girls you see on TV are who you will meet when you sign up for dating networks or that they really used crest whitening toothpaste to get their perfect smile? Fuck no, write your own testimonials and make them say whatever you want. Throw a disclaimer in your term of service page that says it is all made up and then only .01% of your traffic might bother to skim through it.
The FTC is seriously cracking down on this shit. If you're promoting your own product, you had better have some good testimonials to use, otherwise your product sucks. IF you're promoting someone else's product email them and ask for some to use.