Often advertisers use social media as part of an integrated marketing campaign whereby Twitter, Facebook and other social media are merely a way of spreading a story. There is nothing wrong with that.
These days nearly every online and integrated marketing campaign has a viral component. If the campaign, more specifically the ‘story’ that it tells, is worth sharing, people will share it automatically. That is the very core of word of mouth marketing.
However, if you plan to make social media marketing a part of your overall communication strategy to be where your customers are, social media are about long term relationships and an ongoing commitment.