There are any number of topics you can discuss with a polymath like Bill Bryson. So why waste time asking impertinent questions about personal grooming? Because sometimes they elicit an interesting and entertaining answer, such as this one:
Q: Why the beard?
A: I think it’s because I’d be frightened to see what my chin looked like. The beard was grown when I was at university and also working at the evening paper at Des Moines, Iowa, and had to be at the office at 5.30 every morning, having been up quite late drinking the night before. One of the casualties of that was grooming altogether. I’ve never rediscovered any of those skills.
You can read the full Bill Bryson interview here.