No, I think the better the final images look, the better the review. One should be able to take it for granted that anyone doing a review has mastered the craft of image making! I wouldn't look upon it as the tester fooling anybody: if he can make it work then so should I. It was never expected from analogue system testers to make duff images to prove something; why with digital?
Of course, in both systems, it really comes down to the genre, and how you want to handle it, compared with what the tester might do. If he doesn't show something that's of great interest to you, then the test is pretty inconclusive and somewhat irrelevant for you. For example, if you shoot people more than anything else, you'd want to see lots of examples of skin tones, and a series of landscapes would prove zilch, one way or the other... In the end, today, where the film comes built-in, you really do need to test first before you buy, if that's a possibility for you. Ditto lenses, where yesterday's reliabilty seems not to exist...