Track changes in cells.
 

I have a few workbooks that contain 6-8 worksheets. These sheets contain
some program tracking data. (Dates, names, times etc.) I have a feeling that
a few of my sites are dumping a bunch of "Dummy" data into the worksheets at
the end of each quarter just to send me some data. Can anyone think of a
creative way to manage this? I thought about creating another worksheet for
each sheet, hide it from the user and track the time and date of the cell
changes in it but I'm not sure if this is the best way. Thoughts???