Yes, be suspect
I've always thought anyone could write several testimonials for the product they're trying to sell and just sign different names - especially on the internet where we're all anonymous, if we want to be. So I pretty much discount all testimonials. I also read an article written by some model who had put on a few pounds (like 15) and was in the process of losing it. She was approached by some diet pill company, to do before & after pics (for which she was paid). She said in prep for her "before" pic, she was told not to wear makeup, not do her hair and wear unflattering clothes - on top of that, when she was posing, she was told to stick her tummy out as far as possible, for the profile shot. For her "after" pic, they did professional hair & makeup & she was in a flattering, great looking outfit - holding her tummy in, too. And....she never used their diet aids, she lost the weight without their help. So it seems at least some of these companies hire models, etc. for their before and after shots.