I recently added a ground-truth tag because I thought that remote-sensing was too generic, and sometimes nongermane, for questions where somebody posts a Google (maps or Earth) satellite image and asks "what is this"?
I don't appear have the ability yet to edit a tag description. I thought it should be something like this:
The things we see from planes or in images can sometimes mislead us. Not only can remote sensing tevhnology leave artifacts, humans have the uncanny need to see patterns where there aren't any.
In order to discover the truth about what we are seeing, it's often necessary to go to the place itself, or at least use our knowledge of the area, or of Earth processes, or the image interpretation skills of professionals.