In his 2006 wrap up, Rick Segal points out some stats he has been collecting.  To the question “Do you believe the VCs you pitched showed you, at a minimum, respect for being an entrepreneur,” 32% said no.  If you follow the links in Rick’s post you can find some stories.

If someone is worth the time for a meeting, be polite and respectful.  If they are worth your time, they are worth treating properly.  There’s no excuse for a lack of basic civility.

By the time they get to a pitch, entrepreneurs have put in a lot of work and have probably made some tough sacrifices like taking time away from family or dropping out of school.  And they are usually extremely passionate.  Those things are all worth some respect, even if the idea they are pitching won’t fly and no one will ever fund it.