While some think this is a moral issue, that this should not be allowed, it is brilliant advertising regardless. Yes, you piss off some people for a couple days, but will any of them really remember in a week? The Food Network and McDonalds received millions of dollars worth of attention from the press and Youtube. This is attention that could not be caught with just regular advertising, and is the end result of something unique.
This can only be a rare occurrence though, because the backlash when subliminal advertising becomes used - besides simple product placement - will be huge. But it follows a famous marketing slogan: Any news is good news.