Several meeting with brand owner within the last 2 weeks really put a new perspective for me. Almost 70% of brand owners are still afraid taking the plunge to social media because they fear of the bad response. It's true, social media can't save you from your ugly product. But i can say this, staying away from the negative reactions and pretend you're deaf is the worst response you can take.
Social media, hence the internet, is a free wild place. You barely can't control anything on the internet, it just runs and it runs big. The virality nature of internet content is almost unstoppable, and frankly I won't suggest you to try to stand against it. But that doesn't mean that brands can only sit in the back seat.
Bad or good, it is the voice of your customer. And trust me, you can't (and shouldn't) silence your customer. And ignoring simply makes it worst.
Try to look at it from marketing point of view. Social media is in fact a marketing effort. I'll tell you will happen, assuming you didn't do anything about it. People will talk smack about you, other people read it and see no response or clarification, they will remember it assuming it's correct. The worst thing, they will influence other people with that false knowledge.
Okay, actually that's not the worst part. The worst part is your competitor, being the opportunist that they are, take advantage of your bad decision and makes your life even worse.
Imagine this : you engage yourself (as a brand) in the negativity dilemma, clarify all the false publications officially and persuade the barer of bad news to a clear understanding. This way, people that read it see how the offended brand to clarify the false issue and your brand image raising up a notch.
Assuming the negative complain is true and correct (which means there's a problem with your product/service) the best thing a brand can do is listen to what customer have to say and at least say that they will consider it. I mean, it's basically a free R&D where you can figure out what your customer wants directly from them.
If this is not good enough for you to understand why your brand should use social media, then i don't know what is.