I think the Nestle Social Media Manager was having a bad day

And it undoubtedly got much, much worse after a lapse in judgment about how to deal with customers.

Here's a suggestion:  Going to war with your customers is never sound business practice and insulting them in this manner just seems petty and vindictive. What was there to gain? When you start in with social media - like Nestle did with their Facebook page - you lose some control over the conversation and you need to be prepared how to deal with that.