This could be a bumpy ride, so strap yourself in. It's something I call the Brand Depreciation Theory.
Often the silos at clients/agencies involved with "measurable" ads add more and more to those ads in order to improve their metrics, their ROI, their clickiness. So in the guise of effectiveness, the consumer winds up seeing communications that are, instead, infected. They're infected with clutter, star-bursts, snipes, exclamation points, exhortations, you name it. Elements that often conflict with building a brand that is likable and honest. Elements that often cancel out the same client's "brand" messages.
Here's another way of thinking about it. Imagine if the Apple store looked like a Best Buy. The store's badness would cancel out Apple's advertising's goodness. And that's expensive.
What the Brand Depreciation Theory proposes is that the true cost of ads described above is never calculated. Because at the same time these ads are "driving response" they're tearing down the brand. They're canceling out other communications from the brand.
And like I said, that's expensive.