Twitter is a popular way to connect with customers. Trends can be followed and shared with customers, sometimes automatically. This post on consumerist.com is an example of being too aggressive. An offshore social media agency for celebboutique.com had misinterpreted a trend -- no doubt because they were not following U.S. news media.
1) Don't rely on a company located physically and culturally far from your target audience to develop and execute your marketing communications.
2) Don't leave your marketing communications on autopilot. You own it, not your agency.