Is there a way to tell just by looking at the dimension when "Dimension Override" is used in AutoCAD?
Yes there is!
One option for identifying manually overridden dimension values is to use the Reset Text Express Tool: The Reset Text Tool is located on the Express Tools tab of the ribbon or enter the command DIMREASSOC on the AutoCAD commandline.
When prompted to select dimensions,window your drawing and the dimensions with modified text will be highlighted.
Need more detail on the Reset Text Express Tool? Here's an article about it from Lynn Allen: http://lynn.blogs.com/lynn_allens_blog/2005/08/dealing_with_ov.html
The Reset Text Express Tool won't identify dimensions with DIMVAR overrides (like DIMLFAC etc.) or exploded dims, but will help for the ones whose values have been edited.
Now you just need to find the valid or crazy excuse the person justified to use a dimension override. Trust me there is not many to justify this potential for disaster waiting to happen when the drawing hit the fab floor or construction site.
This common question was identified and a solution sent to me from my Autodesk colleague and good friend Chris Miller of the AutoCAD Test Development team. The AutoCAD Test Development team receives a great deal of bug reports and feedback and some are common and we can point out solutions to help you such as this one.