ORIGINAL:
However, this is where we part company. Go back to the torque rings and think about what you are seeing. You are looking at the "track" that the prop tips are following as the prop advances through the air (it doesn't matter if the plane is stationary, the props are still advancing through the air). Keep in mind that they are driving the slipstream, rather than being driven by it. What you are seeing is an interconnected series of loci showing where the prop tip was a few moments previously. You see exactly what you should see in a prop turning clockwise. The slipstream is indeed swirling from left to right, as the prop tip is moving from left to right.
Ahh but... The swirl theory is based on the assumption that the propeller imparts energy to the air particles that causes them to move in the same direction as the propeller. This is the source of the clockwise rotation. The problem with this is that it violates airfoil theory. Air particles moving over an airfoil are forced down and AFT. To make the slipstream work they'd have to go down and FORWARD! (neat trick if you can do it) I have access to a book written before Stick and Rudder that points to a mathematical solution showing that the airflow from the propeller is a winding sheet bounded by the propeller root, or the fuselage, and that vortex we see in the picture. Again that sheet has the air flow running around the fuselage in a counter clockwise path. Or at best straight back from the prop. Again no swirl in the slipstream. Then again try to find a shot of an aerobatic airpane with smoke on in just a straight high G pull up. This is where the slipstream says stuff should be wrapping around the fuselage. Yet I've been unable to find anything like that.