If you’re going to have a Twitter account, then be active. If you never update, then not only is your account useless, but people will likely unfollow you. At the same time, you might also be deemed a lurker if you never respond to a single @reply or direct message. If you’re President Obama, sure, it’s understandable that you don’t have the time to answer @replies. But if you’re just some average Joe blogger, then you certainly have the time to stay active and engaged. Everyone’s probably been guilty of this at some point, but don’t make it a habit. You have a Twitter account for a reason. Don’t waste this valuable tool. Be social.