Rated 5 out of 5 stars

A must-have indeed. Just have a look at the following article which refers to 'BetterPrivacy' as a, if not "the" solution (for Firefox users anyway) :
http://www.helium.com/items/1905717-zombie-cookies-what-zombie-cookies-are-and-how-to-delete-them

This review is for a previous version of the add-on (1.48.3.1-signed).  This user has 3 previous reviews of this add-on.