Without a specification the correctness of a program is necessarily undefined. This means that most buggy software isn’t incorrect. In fact most buggy software

Without a specification the correctness of a program is necessarily undefined. This means that most buggy software isn’t incorrect. In fact most buggy software isn’t even unpleasant, at least insofar as users prefer using it to not and continue to pay. It follows that as commonly used the term bug refers to a pleasantness defect rather than a correctness defect. And this stands up to our day to day experience. In the overwhelming majority of cases users report bugs because they are displeased by a behavior, not because they studied the specification and discovered a correctness error.