It's been so many years since grad school that I can't give you a detailed rundown.

Phrases that come to mind, however, include:

"endless deductions from baseless or questionable premisses, each increment more likely to get farther from the truth rather than closer"

"tendentious arguments against a straw-man Enlightenment Project"

"unhelpful, unwarranted reductionist view of post-Hobbesian human life and society as a cynical power struggle"

"caters to his own paranoid leanings and encourages the same in others"

"ingenious enough to open up a new but largely sterile field for doctoral candidates and played-out junior faculty members in need of tenure"

"impenitently obfuscatory"

"attacks the very liberal humanism which, even if epistemologically illusory, has freed a billion people from absolutist, pre-Englightment-style rule"

"If he's correct, should we prefer political and linguistic anarchy?"

Etc.

Of course I realize that by claiming the emperor has no clothes (or, in Foucault's case, no more than a tattered Nehru jacket) I prove myself to be one more zombie brainwashed by the manipulating gatekeepers of knowledge - and the more shadowy powers behind them.

Unlike Foucault's own, more trusting brainwashees.

(I won't argue with his idea that semantic categories constantly shift but he didn't come up with that one himself, and we have proof it's true.)