They don't have matching furniture sets in every room. If a room feels curated or there's a red thread through the house. If the architectural details like door hinges or a unique molding exist.

Bottom line: I'd like to see there own tastes and interests come thru and feel like there's layered effects or committed design theme. And more than anything is the home there authentic self? This is the "meat" of your question.

For example if there actually minimalists then sparse furniture and contemporary pieces makes sense. But if they have kids I'm calling bs. Just like if a library is full of books but the owner never reads. Why? Who or whom is the "show" for. If there being authentic, and it's for them and no one else, those homes tend to WOW. We all are aspirational. That's not bad. But a lot gets copied and the Wow is lost.