This article documents a small bug of the Visual Studio code model:

BUG: EnvDTE80.CodeEvent.Comment doesn’t return “” for C# events without doc comment
http://www.mztools.com/articles/2011/MZ2011007.aspx

The bug report that I filed to Microsoft Connect is here:

https://connect.microsoft.com/VisualStudio/feedback/details/652387/envdte80-codeevent-comment-returns-doc-doc-instead-of-for-c-events-without-doc-comment#details