Some brands are very successful on Twitter. They might be using it for customer service, to engage with customers or to discuss issues that they might be interested in. For many brands, Twitter is a great way for brands to engage directly with consumers, to learn what they are saying and to react and respond to this where relevant.
The question for many brands, though, is why would people want to engage with them on Twitter. In some instances this is clear. For example, when Twitter is being used as a servicing channel it is a way for customers to ask questions, complain or get support. In other instances it is less clear. And as with any social media strategy, it is critical that you think about why people will want to engage with you as much as why you want to engage with them.
When discussing this with clients and others recently, the question that always comes up is if brands should aim to gather a lot of followers on Twitter (as opposed to engaging a lot of people regardless of whether or not they follow you). And with this goes the question of whether brands are expected follow people back who follow them.