Two and a Half Men is bad television, but Downton Abbey is BAD television. The difference as explained by Fussell is that "bad" is just poorly executed while "BAD" is also pretentious. A dinner at Burger King might be bad, but a dinner at a pompous bistro where more effort is put into the creative writing in the menu than the actual cooking is definitely BAD.
The twenty years that have passed since the publication of this book make some of Fussell's complaints almost quaint, for example he complains about BAD newspapers but now newspapers are almost a thing of the past. At his best Fussell is a sharp cultural critic with a bit of a condescending elitist edge; at his worst he comes across like a tired Andy Rooney piece from 60 Minutes about how nothing is as good as it used to be.