I've been thinking about this recently: drug addicts "seem" unhappy because they don't match the usual outward appearance of happiness. But who's to say in their lifetime they haven't experienced many orders of magnitude more happiness than even the happiest non-addicts? Drug addiction breaks the usual profile of happiness, it doesn't mean that they're not actually the happiest people who ever lived.

Well that's possible, but then you'd expect some of them to self-report great happiness.

Once we go far enough down the "who's to say" route that we ignore self-reports for happiness, I'd say the term loses meaning.