It's more the paid US propagandists / trolls that need to be watched out for. The US gov’t contracts companies to set up and pay people to post with fake puppet accounts to promote US policies and ideals, while attacking opponents of US policy and its ideals.
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https://www.theguardian.com/technology/2011/mar/17/us-spy-operation-social-networks
https://www.theguardian.com/commentisfree/cifamerica/2011/mar/17/us-internet-morals-clumsy-spammer
http://www.reuters.com/article/us-election-intelligence-commentary-idUSKCN10F1H5
http://www.businessinsider.com/ndaa-legalizes-propaganda-2012-5
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Here’s some excepted information from the above links:
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According to publicized 2011 USA Central Command documents and contracts which detailed the program, The USA has "by far" the world's largest cyber-army, and contracts companies to set up and pay people to post in social media "around the world," "using fake online personas to influence internet conversations and spread pro-American propaganda."