I am often troubled by comments that friends make - allowing the statements to go unquestioned would go against everything I'm hoping our society could achieve. On the other hand, however, I need to balance the desire to keep my wife from getting mad at me for "offending" a friend.
Typically I simply try my best to avoid topics where pure stupid can be exhibited by those who have done little (no) research on the area of discussion. However, there are times when it is inevitable, a topic is being discussed that asks for (no, requires) a response.
When my friend responded with a statement of idiocy (when they gently punched my shoulder I joked about having just got my flu shot (I got it months ago) but they responded about not getting the flu shot because it is a "scam" - they referred to homeopathy, at first, and then vitamins and supplements - for the record they were unaware that homeopathic "remedies" were not the same as "herbal remedies" nor did they know that 200C meant "1 drop in 'there-aren't-that-many-drops-of-water-in-the-whole-universe"). I stopped, for a second, and weighed, quickly the benefits and drawbacks of responding. My skeptical side won out (to the chagrin of my wife).
This person suggested that they (and their kids) take an homeopathic (or herbal - it's the same thing to them! :) ) "treatment" and the kids "never get sick" but "when they do get sick, I give them X treatment and it works". Either the kids "never get sick" or they do - but no time for semantics. Mark Crislip (http://www.quackcast.com/) mentioned a quote in one of his podcasts that I often attempt to repeat (but fail miserably as you'll see): "If you have a common cold and take an over-the-counter cold remedy, you'll get better in about 7 days but if you don't take anything, your cold will get better in about a week."
Regression to the mean, the natural history of the disease and the FACT that most (all?) common cold viruses are self-limiting often result in people attributing a causal effect of a (non-)treatment with the improvement of a set of symptoms. The anecdotes that follow seem compelling and interesting but, as far as evidence goes, anecdotes are of little value - whatever the plural of anecdote is, it is not data.
I thought I would speak to them, a bit, about Airborne but when I mentioned the product, they quickly responded with "yeah, that stuff works great, I take it before I travel or when I start to feel a cold coming on". It put a smile on my face, I could hardly hold my excitement. Airborne was falsely claiming that its product could prevent the common cold or reduce the effects of it and the FTC called them on it - as a result they had to refund purchasers' money (http://www.washingtonpost.com/wp-dyn/content/article/2008/08/14/AR2008081403142.html).
Explaining the airborne refund lead my friend to ask "why are you so cynical?" It is a question that skeptics, on occasion, will have to face. Ironically, we're not the cynics - we have a positive view of the strengths of science and humanity - someone who believes in homeopathy or is anti-vaccine or believes that 9/11 was an inside job (activate comment trolls!) is cynical - they're suggesting that the "medical industrial complex" or "big government" is actively trying to profit with no regard for their fellow humans/citizens. We (skeptics) have a positive view of humanity, not a cynical one. We just happen to require a little more evidence before we accept a life-affecting proposition.
Skepticism is a positive and healthy approach to take. It is educational and rational and can help one avoid scams, health risks and abuse. So go out, be skeptical - you're helping, not hurting, your fellow human, your family and your planet.
(As a side note: Ironically, this person, who is rather against the idea of germ theory (seriously!), carries around a container of anti-bacterial hand wash.)