Honestly I think testimonials may help a bit as a host, but in these days of abuse I don't think they are overly effective. You just see one too many fakes out there and it removes a potential client's trust in them. I think that perhaps testimonials in say a forum might have a more positive effect, but they're still open to abuse.

As a user, I do tend to read through them just to check them out. Quite often it's easy to tell if they're fakes or not IMHO. Even if I don't deem them to be false, I still don't put much stock into them. Typically I try to rely on independent sites for reviews if I at all can.