Originally posted here August 2009 and still true with Revit 2013
When an architect uses the Basic Ceiling-Generic type they are creating a situation for the Revit MEP user they may not be aware of. Face based content does not orient themselves to the correct side or face of this ceiling. For air terminals and others this means they are usually upside-down. I created a short video to demonstrate what I'm writing about.
You can listen and watch below:
Here's an image to convey the issue without watching the video. The left side is a Basic Ceiling and the air terminals are upside down. The right side is the Compound Ceiling and the air terminals are okay.