Oh, I feel for you there. Is it Kentico or DotNetNuke? You may not be able to answer to protect your anonymity, but my condolences if it is. We've done cleanups jobs for both of those and...oh, the kludge.
I've been treated (exploited?) in much the same way as you have in the past; it sucked at the time but I'm a better carer-and-feeder for developers because of the experience. :)
And I wish it was Drupal, he refused to move away from .NET. I will say the CMS we used is the worst experience I ever had. It is horribly bloated.