Someone asked the following, so I thought I would try and address the issue as I think it is one that is commonly misunderstood:
Could you enlighten us on what happens when an Outlook...
Published May 01, 2006
Version 1.0
Blog Post
Nick--
In reference to your first point, I am always a proponent for starting from a clean slate as you never really know what you are working with you are trying to clean up someone else's mess. Using ESM, you can remove Delegates and those accounts with "Full Mailbox Access" and/or "Send As" permission. However, this will not clean up the folder permissions as this is done by Outlook when Delegates are removed.
If you are having some serious issues with Calendaring in Exchange, I would strongly suggest that you contact Microsoft PSS. They are going to be your greatest resource for trying to sort out your Calendaring issues.
If you would like to do some initial investigation into the "health" of your Exchange Organization, you should download and run Exchange Best Practices Analyzer (ExBPA): http://www.microsoft.com/technet/prodtechnol/exchange/downloads/2003/analyzers/default.mspx
--Chris