Originally Posted by
TromboneAl
I actually always try to locate the puncture before removing the wheel (feel for object, pump up and listen for air), and succeed about 20% of the time.
Since you're trying to find a reference point anyway, if you always stuck the tire label at the same spot on the rim (like the valve hole, say) then you would have a better idea of where to find the offending object once you've removed the tube. In either case you'd still have to put some air into the tube to find the hole(s) to patch.