@Earnst: Employees often opt to access social media through their phones while at work, not their PCs, so to circumvent any possible Internet surf "issues" tied to agreements with their company. Phones offer plenty of convenience and access to use, without the easy traceability of using a company's network. And while many workplaces have phone-use policies in place, phones are a less-salient and more difficult for management to track. (If not witnessed first-hand or on camera by supervision, work productivity report compilation is required--work lazy or over-worked managers don't do).
While I've implied that some at work are using company time for Social Media (regardless of what they're posting), that's not a completely fair treatment: Some comply and save posts for breaks or lunch.
At that point, the issue falls back to First Amendment rights. As individuals or employees, we have the right to say what we wish--but we also face costs for our actions.
Companies don't take kindly to dissenters, and have the leverage to take--and get away with--various actions (including quick disposal of employees) to protect their PR image.
Translated: Tweeters beware!
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