bluffing in spots where the opp cannot be strong is extremely effective (provided you rep some hands) since most ppl are too bad tto realize their opp cannot be strong.
(+ its so hard to realize you are being exploited there)

.. whether or not your opp can have AQ in his 3betting range on a Q high board is a really, really big deal
-> you can float Qxx when you call his 3bet since he cant have AQ, KQ there