Look for the product approval label on the shutters. The product approval label is usually a silver-colored sticker that has a product approval number. If there is no product approval label, then the product has not been tested by the county and will not be legal to install.
Test the shutter with a level. Put the level on top of the shutter and see if it's straight.
Close the shutter and evaluate if it closes correctly. Do you need to use too much force to close it? This could be a sign that the shutters were not installed correctly.
Test the lock on the shutters. Use the key to close the shutters. Try to open the shutters, and see if the lock holds the shutters closed. If the shutter opens, it's most likely improperly installed.
Call the local building department and ask them how many screws are required per square feet of shutter. Count the screws and see if the installers missed any.