Do you ever become impatient with incompetent folks who swear that they can successfully multi-task? I do.
Let me go further by proposing that anyone who claims to be a successful multi-tasker is automatically incompetent. Scientists have concluded that we humans can focus only on one task at at time. Therefore, performing more than one task simultaneously consists in applying "continuous partial attention" to the tasks. (I got that phrase from today's Wall Street Journal.)
I'm going to add this to my list of interview questions: Can you successfully multi-task, and can you give me an example of your success at multi-tasking?
Just imagine how the interviewees, eager to make a good impression, would fall into my trap. Not only are they incapable of focusing, but also they're incapable of acquiring the introspective knowledge that would enable them to recognize what focusing entails and how they fall short.
Or, I could just dismiss them as blasphemers for claiming possession of what appears to be a divine attribute.