I ask myself what I like about the outfit specifically:
Then ask myself if that aspect is something that
I also try to ask myself if I like the outfit itself or if it's really the lifestyle portrayed in the photo that I'm really drawn to. It's easy to get charmed by a pinterest photo that portrays a rustic boho or edgy office exec lifestyle or whatever, but if that doesn't really jive with your own life then perhaps you can save it to a themed board, but not your personal style board.
Seconding coffee_for_dinner's advice and observations about regularly taking photos of your own outfits.