The last time PetVille offered free Clean Bombs for fans was April 27th. Clean Bombs are a premium item in PetVille that allow you to clean your house and pet in one go, while earning you double the Coins and Love (i.e. XP points). Currently, PetVille sells a 5-Pack for 3 Pet Cash, and 50-Pack for 25 Pet Cash.
But you can get one for free here
! All you gotta do is become a fan of PetVille's official Facebook page