I think part of the problem is that many people can't appreciate just how slick these conditions were because they've never experienced it. I've ran into it a few times, and it was like a carnival game. What you think is a stop shot gets you 8-12" of draw, and side spin seems to have almost zero effect off of the cushions. Actually, the slick conditions are the reason Corey ended up with the kick on the 3 to begin with. He had room to follow and miss the point on the side pocket, but the cueball slid right into it, resulting in the hook. Get some new 860 and grease up your cueball if you want to experience it for yourself.
Aside from that, the only other proof I can provide is this:
When the CB hits the 2nd cushion, the ball is still spinning such that the "measles" are indistinguishable from one another This is still true when the CB contacts the 3rd cushion, indicating that very little of the spin rubbed off, even after the "wrong-rail" hit on the 2nd cushion. Then, despite the still considerable spin, the CB's change in direction off of the 3rd cushion is very minimal - just a few degrees I think. On a table with worn-in cloth and marginally clean balls (what most would call normal conditions), that amount of spin at that slow speed would cause the CB to completely reverse its angle and head back toward the left long rail. Instead, it only shortens by a few degrees.
The reason we don't see a dramatic direction change off of the first cushion is the same reason we don't see a dramatic direction change off of the third. I am convinced that there was considerable spin on the ball when it contacted the first cushion, although Pat and I have different opinions on how it got there. Usually the only way you see that much spin transferred from ball to ball is on the break shot, where the ball is "pinched" and receives complementary rubs from 2, 3, or 4 balls at once.
Aaron