Let's get this out of the way first: yes, it's true. I frequently sing Show Tunes while on the job. Luckily I'm a dog walker, so the complaints are few.
Lyrics stick with me. It's a gift. And a joy. Even so, when it comes to selecting music to listen to, most of the time I choose instrumental Classical music. Since I'm most drawn to Baroque and Classical styles, maybe it's the strict patterns that I find pleasant or perhaps, soothing. After all, once the Romantics and Moderns got into the act, things went looser and well, less soothing.
A Jazz enthusiast once got in my face; calling me uptight, conventional and unimaginative. Jokingly, I suggested that because I go to bed early, I've never experienced real live jazz in smoky night clubs. Therefore, I never learned to fully appreciate jazz. That explanation fell on deaf ears. Instead I was deemed too closed off emotionally to appreciate the spontaneous innovation of jazz. That's just plain poppycock. If I was closed off emotionally I wouldn't be inclined to lustful thoughts of Gene Kelly.
But lets return to our musical discussion. It could be, that my ears prefer to separate sensations. Voice is meant to be more wild and free. While strings and woodwinds and pianos sound better with more structure. Give me scatting Mel Torme' or Ella Fitzgerald. But keep the piano Mozart.
Maybe music is like religion to some folks. That would explain the Jazz Zealot's heartwarming inclusion and acceptance toward other musical faiths. Like most things, of course, it's not all that complicated. What is music to you may not be music to somebody else. It's really just a matter of keeping the volume down low enough not to force others to listen and just high enough to enjoy it yourself.
As for me, I shall sing 'Whistle a Happy Tune' and 'I'm Called Little Buttercup' while I walk and listen to The Brandenburg Concertos while I drive. As I type this, Yo Yo Ma and Emanuel Ax play Beethoven.