Anil Dash, who has fine linguistic sensibilities, talks about language(s) in entertainment and politics (which, these days, is getting hard to tell apart):
Linguists use the phrase "code switching" to refer to the act of using more than one language when speaking. As someone who grew up in a multilingual household, I'm intimately familiar with code-switching, and one of the most interesting traits about the practice is not merely how easy it is for people to switch language on the fly, but rather how the choice of language actually informs the meaning and the nuance of the words being said.
This gets even more pronounced if we use an expansive definition of the idea of "code switching" and include switching between dialects of the same language. Then, we can look at some familiar examples to learn from them.
For example, Oprah Winfrey is an extremely successful businesswoman, obviously well-versed in the General American or Standard American English that's the language of business in this country. But Oprah regularly and effortlessly code switches to AAVE (also known as "Black English" or, to its detractors, ebonics) on her show or in various media appearances. Though her use of the dialect is clearly sincere and authentic, it's also obviously a savvy way to stay connected to audiences with whom she wants to maintain a particular resonance or credibility. In short, code switching is an efficient way to target a particular message to a particular group without explicitly telling the world that's who you're speaking to. The context makes it obvious.
We see George W. Bush do the same thing regularly, as well. No man who has an MBA from Harvard and grew up among the most privileged families in the United States can be unaware that "smoke 'em out" isn't Standard American English. That's not to say his use of folksy sayings is merely a put-on, but rather that it's a linguistic choice he makes in some settings, and with the same goal as Oprah: He's speaking directly to a particular audience in a way that resonates with them as credible, and signifies to others that they're not the target audience for his words.