Most fixed magnet pole pickups (Strat, Tele, some P-90 and some humbuckers) have a magnet stagger with a compensated G magnet which is set low. A right hand pickup turned around to left hand causes a huge loudness im-balance between the D and G strings. Pickups with adjustable screw pole such as most P-90 and Humucker are not discriminating because they can be adjusted for both left and right handed guitars.