It is appalling to see how badly used some terms are, particularly during debates involving emotional people. A look at the comments about Mark's review for the Vegetarian Myth is a good example of it. People calling each other dogmatic and closed minded all over the place.
Here are some definitions:
Freethought holds that individuals should neither accept nor reject ideas proposed as truth without recourse to knowledge and reason. Thus, freethinkers strive to build their opinions on the basis of facts, scientific inquiry, and logical principles, independent of any logical fallacies or the intellectually-limiting effects of authority, cognitive bias, conventional wisdom, popular culture, prejudice, sectarianism, tradition, urban legend, and all other dogmatic or otherwise fallacious principles.
Skepticism is an approach to accepting, rejecting, or suspending judgment on new information that requires the new information to be well supported by argument or evidence. Individuals who proclaim to have a skeptical outlook are frequently called skeptics, often without regard to whether it is philosophical skepticism or empirical skepticism that they profess.
Dogma is the established belief or doctrine held by a religion, ideology or any kind of organization: it is authoritative and not to be disputed, doubted or diverged from.
I think it is important to add that the difference between a fake and a real skeptic is a strong and genuine commitment to finding the truth, regardless of how uncomfortable or counter-intuitive it might be.
A honest pursuit of the truth demands a genuine commitment to weight evidence for or against a given position, deciding accordingly, and remaining open to new evidence that might merit a re-evaluation of the previously addressed claim.
Also, there is a big difference between intelligently questioning an idea, or just throwing random ideas in hope of validating a position commonly seen as silly or false. This is the case with many creationist and evolution "skeptics", for example.
And finally, it is clear to me that not all opinions are "born equal". Every is entitled to an opinion, but that does not mean that all opinions are worthy of respect.