It's crazy how often this kind of thing happens and how predictable it is every time. Rene Ritchie absolutely nails it with his analysis over at iMore:
Does it make the celebrities look duplicitous or for sale? Does it make the vendor look silly or desperate? I'm not sure. I do know that if you're Samsung and the celebrity that you want associated with your brand really uses Apple, paying them to pose with your phone isn't a viable solution anymore.
You can blame it on PR people, social media people, or whatever, but even where that might be the case, those people are still not using the products the celebrity has been paid to use. They're using Apple products.
Make a phone the celebrities (and their "people") want to use even when you're not paying them. Do that, fix that, and the social media problem and buzz marketing fixes itself.
Unless and until that happens, we'll likely see more product placements gone wrong. Or right, if you're Apple.