Today, my wife has shocked me by telling me that a scarf does not and cannot help a sore throat. I could swear that it works wonders for me!
Pretty much the entire knowledgable Internet seems to agree with my wife (a scarf does not help), but at the same time they report on a widespread usage in Germany and other countries.
The only reasonable report in deference of my experience I could find is this Yahoo.Answers question:
Q: My mom always put us in a scarf when we were getting or had a sore throat. Was that an old wives tale or does it actually help?
A: Actually it does work.
The tradition comes from Northern Europe and especially Germanic countries.
No one knows exactly why it helps, the theory is that it raises the temperature of your throat very slightly but that is enough to make the environment more hostile to the infection. Thereby giving your immune system a chance to respond to it and clear it from your system before the infection has a chance to get serious.
An other possible mechanism is that the slight warming helps draw immune cells to the area, speeding recovery.
I wish I could locate the reference right now, but about 3 years ago there was a large study that showed a statistically significant shortening of symptoms in the group that wore scarfs as soon as they started to get the first signs of a scratchy throat.
It mentions that there's a conclusive study that shows that scarfs do indeed help, but it fails to give any reference to the study, and Googling/Bingling/DuckDucking does not help me either.
1) Do we have any studies that show that scarfs do or do not work?
2) If there are no studies, do we know the answer by other means? Is that quite certain, or can there be some reasonable doubt?
3) If the scarfs do not help, how come so many people believe that they do, from their own experience?
UPDATE: Looks like nobody has any definitive answer, and perhaps nobody has even worked on collecting any real data. So I'll describe my own experience. Perhaps comparing experiences of multiple people can get us closer to the answer.
Not a childhood habit for me (as far as I remember). Picked it up when I was 18-19 y.o.
When my throat gets sore, it gets sensitive to outside temperature. When it's cold outside or there's an air flow close to my throat, I feel as if it's getting dry inside, and as if it's aching more. With a warm scarf or blanket, the throat quickly gets comfortable and starts feeling as if it's getting better within 1-2 hours.
The best perceived effect is, of course, after sleeping through the night with a scarf. (This is useless info, because sleeping through the night should give the best improvement with or without scarf.)
I propose a theory that a sore throat feels comfortable when it gets warmer, and the comfort might be producing a measurable effect on the overall illness.