I had doubts as to the validity of the content of this post, so I emailed an aerodynamicist/full size friend of mine who confirmed my misgivings. Here's what he said...

"Stalled wings are not something that aerodynamics books dwell on, because they are not much practical use. But let's start from "What is a stall?"
The stalling angle of attack is the AoA at which the wing reaches its maximum Lift Coefficient. Push it beyond that angle and it develops a bit less lift and an awful lot more drag. It's the drag increase that makes the aeroplane fall out of the sky as much as, maybe more than, the lift reduction.

These 3D models with very little weight and huge amounts of power are probably capable of flying with the wing at AoA beyond the stalling angle. I wouldn't like to analyse the flight or write equations for it because it's not something I have studied, but with abundant prop thrust overcoming high drag and helping to support weight, why not?

But at AoA below stalling angle (which could be from 6 to 12 or 15 degrees depending on aspect ratio and other things) these thin symmetrical or flat plate sections will behave fairly normally. The airflow will flow in streamlines around them, though they may have a bit of a separation bubble especially near the LE if it has a sharp corner. That might cause odd kinks in the lift curve, so sharp corners are best avoided.

The tails on regular models will virtually always be flying normally, i.e. not stalled. As long as the wing is not stalled the tail will not be stalled either I would say.

I'll bet these shock flyers spend a lot of their time not stalled either. Their straight cut depron wings may not be very efficient and may stall a bit early and may have little areas of separated flow near the LE but at low AoA they will behave quite normally. I would suggest wrapping the LE with tape to round them off a bit."