Every year. Without fail.
My wife worries about it, reminds me to be careful & prepares accordingly. Still, the same thing happens to me. The first year we were together - a week before I went to San Diego (to run a marathon & work on the Navy base at Point Loma) for three months - was the worst.
Last Thursday morning was not nearly as bad, thank heavens. My alarm went off at 5, after a short tempo run the evening before, followed by a couple of beers. I woke with a nasty glob-like feeling & discomfort at the roof of my mouth. In spite of my best efforts to fight the histamine-based assault on my upper respiratory system over the next three days, my breathing this morning is not good. It's nearly impossible to run when your throat is clogged the same way as if someone shoved a running sock down your throat. So my "easy" 30-to-60-minute run this morning was replaced with a trip to Wal-Mart for more & better medications. Better to nurse a low-level upper respiratory infection for a few days than try to train through it & end up with a full-blown fever, like when I was training for San Diego.
I've learned in the past eight-to-ten years to say no to an excess of parties & social functions. I don't have a hard time doing that; I'm socially-inept at baseline. But some environments are closer to a petri dish than others - ask any schoolteacher. I can be mindful of my exposure risk, & try to mitigate accordingly. But, it still seems my closest friends & contemporaries will wear themselves down during the holidays, catch something...and pass it along to me.
So where is the line drawn between the "go for a run" decision, & the "curl up on the couch & watch Man v. Food" decision? The chin.
If you have got the sniffles or some congestion in the head, an easier run is not likely to kill you. If the congestion is in the chest (If you are using what are called the accessory muscles to help you breathe, the answer is "yes, it's in the chest."), I'd recommend watching Adam Richmond get stupid with 15-dozen oysters.
But in case you forget this by the next holiday season, I'll stock up on the Vicks VapoRub.