My wife used to yell at me because the bathroom sink area was constantly a mess.
When we built our new house, a few years back, we had enough room to build his and her sinks.
That's when the truth came out. My side was always spotless, and hers was a wreck.
She's been quiet ever since.
It's 2 to 1 evidence here. The sinks used by my wife and daughter quickly become well, disgusting. Mine is relatively spotless. It's hair and makeup mostly.
My wife and I share a bedroom, but when our daughter moved out and we moved into a two bathroom unit, it was one of the most pleasant experiences of my life. I'm a big advocate of separate bathrooms.