[embolalia]

The issue is that plenty of people come in spouting complete nonsense that they "know" about their health, and they're usually wrong. It creates a default reaction. Imagine someone coming in and saying they can't send emails more than 500 miles. If you'd never heard [that story][1] before, you'd probably think they were being ridiculous. They may be absolutely right, but it sounds so different from what you know that you default to saying "Email really doesn't work that way, generally." It doesn't help that you're used to people coming in and saying that a virus put porn in their browser history.

[1]: http://www.ibiblio.org/harris/500milemail.html