No ridicule. This topic comes up often. The problem with NM cable is that the wire ratings are marked on the outer sheath and as such can only be installed inside walls and in dry locations (and JB's for switches and receptacles with device covers on in bathrooms are still considered dry locations). The internal wiring in NM is also wrapped in a cardboard-like paper. It is possible that condensation could weep through the jacket and dampen the paper wrap and possibly corrode the wire over time. Now, if you look at MC cable, in contrast, the individual wires are marked before the armor goes on. So, my gripe is with manufacturers, and I'm sure it's a cost of production thing, but why can't they mark the wires or use THHN II before installing the sheathing ? That way, if you run the internal wiring say to an AC disconnect you can then use the same wires inside the whip to the unit.
Anyway, I would say that if you intend to install wiring in PVC on the outside of the house, use UF cable to solve that problem.