I've learned to do this as well, and as a consultant it's become part of my job, so I've picked up a couple of extra tricks. One kind of WTF that isn't usually

I've learned to do this as well, and as a consultant it's become part of my job, so I've picked up a couple of extra tricks. One kind of WTF that isn't usually obvious from looking is when doing what looks like a simple thing takes excessive time and effort. Sometimes, after a couple of weeks, you can see something that has been in progress but not completed for no clear reason. Oftentimes these extra effort things don't show up because the team avoids doing them unless absolutely necessary. It's worth asking a team member for a tour around something you know from past experience in similar situations should be easy and quick. A big tell is when the response to your request for a demonstration or explanation involves a need for someone to block out extra time or involve a specific individual who knows it best.