RE: Dull broadheads = Bad flight ??
More often than not poor arrow flight with broadheads is the result of arrows poorly spinedfor the bow. Then there's the issue of forgetting almost everything you know about paper tuning and tuning with field points and tuning for your broadheads.
Most tuning of hunting equipment is done backwards. We paper tune for bullet holes then sight in with field points. Tune your bow for good broadhead flight, with properly spined arrow, and most often your field points will fly well, too.
Easton's Tuining Guide is almost a bible for tuning.