Cargul, that is an urban legend. I've been friends with many owners of gaming stores, and he says everyone has their own idea about "where the best are", but in reality, there's not really a provable system to make.
I have bought booster lots from HWG several times for both myself and resale. One of my customers was very happy with what he got in some of these lots, which included a Witch King,
Greenleaf, and Gorn's Bow. I recently opened some towers packs and pulled a couple main character rares.
I think you're pretty safe in buying booster pack lots.