Thanks Chuck.
I see the functionality on your site and I verified the code is correct in search.php, but for some reason on our site, a search within "reviews" is returning products without reviews. You can see for yourself at:
http://ir7.theimagingresource.com/reviews/search.php
- Set to search "Best EF Lens".
- Set to "All Reviews".
And the first result returned is a product without a review.