Sometimes, when you answer a question, the person asking it realizes that the answer is not what they wanted, and the changes the question in a way that renders the already given valid answer invalid.
I call these chameleon questions (from a term coined by Aarobot), and while his definition is closely linked to morphing code questions, I think the term can be used more widely.
I dislike this, as it sometimes make you appear like an idiot when your carefully written answer suddenly changes into a non-sequitur.
Is there a way to discourage this?