A good friend who runs an audio accessories company (one of the good guys - not a snake oiler) visited the Wilson room when David Wilson was still alive and at the helm. After listening for a short while, he said quietly to Wilson "I think one of the midrange drivers is connected with the wrong phase"
Wilson went into a major rant, that it was impossible a driver was wired incorrectly - yak yak yak.
My mate shrugged his shoulders and went back to his own room. After a while one of the Wilson techs came and apologized for Wilson's rant, and told him that he was absolutely right - the left hand speaker has one of the mids antiphase.