I got to thinking about this while reading the $5 wine thread.
Is plonk BAD wine, i.e., defective, thin, unbalanced? Or is it simply good sound wine that is not particularly distinctive?
I think the $5 Spanish and Portuguese wines I've been buying (for example) are sound and creditable, but not fascinating. Good everyday wine. There's no reason to denigrate such wine. You'd probably be served such wine at an average restaurant in those countries; would you reject it as plonk?
Is life really too short to drink such wine? Hardly, I think.
I'm just trying to get clarity on a definition here.