The problem: Users are mirroring casework and furniture elements and some of those items are not supposed to be mirrored because they have very specific manufacturer codes. A left-handed version has a different code than a right-handed version so mirroring will create a right-handed version that looks like a left-handed version. Tracking this situation down isn't easy the way Revit is on its own.
Enter Model Review: (it was called BIM Review before). We can create our own review criteria that will check the model for mirrored components. This is a default condition that exists in the Model Review configuration and it is easy to use in your own Check file. Rather than spending a lot of time itemizing the process in text here the video will cover that. I've posted the example file so it can be downloaded if you are interested in reverse engineering it. Technically you can just reverse engineer the existing templates...that's what I did.