Not Old People Smell

Is being a super smeller a blessing or a curse? I'm always chasing down the source of something that doesn't smell right in the house. I always thought the musty smell that gathered by the front door was the cat food scent wafting toward that nook and getting stuck there. But the cat food is long gone and when I leave and come back to the house, there is that not- so- good- scent. My first thought last night was, "Oh no, not old people smell." I decided to keep the kitchen drain covered to see if the 50 + years of plumbing might be the culprit. It's kind of impractical to keep a drain closed, but as smell detective / deducer, it's a must.
Please don't let it be old people smell.
When I was about 9 years old and taking ballet lessons, our teacher brought us to a lady's house for costume fittings. The 2 other girls and I all hated the smell of that lady's house. We went back 2 other times, and it didn't hit us as badly, but that smell was there, none the less. That lady, in my mind, certainly qualified as "old," but could she have been my age now?
I didn't know of old people's smell syndrome then, but it's one of those known facts that we must all learn from osmosis.
Hubby asked me why the drain is covered. I told him that I keep smelling a musty scent. He replied, "do you think it's old people smell?" We have never discussed this issue in our near 25 year history, yet, there it was lurking, waiting to reveal itself. Does he think we are doomed for our house to grow old with us. Do we smell? What is that smell?
But as a super smeller, I am always asking that question.