So we had an issue recently where a bit of code that we do not have the source for and is obfusticated (grr) was making a series of inserts and updates to the database that were causing some issues elsewhere.
Being that it was a many stepped process we weren't sure what the impact would be or even what all it was changing.
Solution: Take a backup of the database, make a copy of it, run the code routine, then fire up Red-Gate's Data Compare tool to quickly find what was modified!