Most of us are familiar with the Straw Man fallacy, and its sister the Principle of Charity. There's a rhetorical device which runs the opposite way, though, where (e.g.) Alice may claim that arguments made against her positions by Bob in fact misrepresent her opinions and positions, but Alice offers no additional clarification. I could offer an example, but I think you all know what I'm talking about.
What Alice's device (apparently) seeks to do, is something enough like moving the goalposts that it could be confused with that tactic. But her charge of misrepresentation by Bob as a defense is, I think, different in kind. This device can be distinguished by its attempt to complain that the Bob is arguing in bad faith. Which could be construed as a particularly insidious ad hominem against Bob (discrediting the arguer), but is nonetheless harder to parry, in that Bob is obliged to demonstrate that he is not hanging the Straw Man, but instead the Steel Man.
What I'd like to know is if this rhetorical device has already been classified. Considering how ubiquitous it is, suggestions for a telling appellation would be useful, if none exist.