Tom Baumbach |
Blur by itself does not allow sneak attack. Blur does grant the rogue concealment, which can be used to Stealth (if the situation allows), and an attack from a sneaking rogue presumably does deal sneak attack damage.
Using Stealth in combat is highly situational and a determination best left to the GM. Player and GM should review the Stealth rules and come to a decision for the group regarding when and how Stealth can be used.