Please note I did not change anything inside the code. It is an installation of Magento 220.127.116.11 CE + Magento Sample 1.9.
1) Go to Dashboard and you will see Best Viewed Products list.
2) Go to Report - Refresh Statistics. Select All and Submit one of the Actions.
3) Go back to Dashboard and Best Viewed Products shows the same list.
Both Actions are not clearing the database for Best Viewed Products. I deleted manually the database and Dashboard shows no products in the list right now. Please check if the other options like Orders, Tax, Shipping are cleaned up too.