You're making an assumption of corporate stupidity that I find to be highly unlikely. Large companies do not become large companies by tossing hundreds of millions of dollars down dark wells without analysis.

I'm making the assumption that Coke and Nike, et al. are smart enough to have at least rudimentary knowledge of the effectiveness of their brand advertising. Is this an assumption? Yes. Is it a more reasonable assumption, a priori, than the alternative? I think so.