What does Mitt Romney’s “I only spent four years as a governor? I didn’t inhale,” mean?
Solution 1:
This joke is pretty contextual.
There are three references occurring in this writer's analysis of Romney's 'I didn't inhale.'
1) Bill Clinton famously claimed that he tried to smoke marijuana but didn't/couldn't inhale; he's been made fun of for this claim ever since.
2) The writer of this piece has an ongoing joke that Perry seemed high, or under the influence of drugs, during the debate. He describes this first as someone having slipped Benadryl (the medicine) into his Sanka (a brand of instant coffee), but the joke transitions into his having inhaled Benadryl dust (to inhale dust is another way to get high, by inhaling a powdered drug). This did not actually occur; the writer is trying to be funny. (Added: Even the writer's reference to Sanka, a decaffeinated coffee, is an attempt to make fun of Romney, who, as a Mormon, abstains from consuming caffeine.)
3) What Romney actually means to say (and the answer to your question) is that he hasn't been overly influenced or tarnished by politics, that he is really a 'private sector guy' and not a professional politician. His use of 'I didn't inhale' - and you'll see this usage other places - means to say that he didn't absorb the culture, here, of Washington/the political world. (This is, of course, a teasing reference to the situation in #1, in which Clinton claimed that, though exposed to the nefarious influence of weed, he did not succumb.)
You may also see the phrase drink the Kool-Aid to describe a total convert who subscribes to something completely. It has negative connotations, meaning the person has been brainwashed and no longer really thinks rationally or for him/herself on the topic.