Bill Hicks on marketing. Pretty much says it all.
edit: I realize this is woefully unproductive for an ELD Forum post, so I'll try to collect my thoughts and include something beyond my righteous indignations.
Long story short, the non-BS approach works better in a world in which information is applentiful, and (conversely, and paradoxically) rational analysis of information is somewhat lacking. Advertisements that seem irrational work because our brains aren't "rational" in the sense that we expect them to be.
As El D said, in order for a rational argument to be more convincing than "SUPER FLASHY LIGHT HOT BABES IN BIKINIS!!!!!", you're gong to need a basis for this argument (your product) that is very, very convincing.