Thanks for the info Stony, you have confirmed many of my theories. If I were doing these parts in SLA, I'd want my A surfaces facing up. Side surfaces will show more stepping in the finish. Seems the same here and the bottom surfaces are the scorched ones. That being said, I've tried to force the orientation to my favor. But I think they pack the printer as much as they can, making orientation choice a random act of violence... I'd be willing to pay extra for orientation choice.
So far I have used dawn and isopropyl in my ultrasonic cleaner. Both work well but also seem to leave a lot of frost behind. Both also really heat up in the ultrasonic cleaner. You would think heat would be good (remove oil and wax) but I'm beginning to think its bad.... I have a feeling the acrylic sub-straight is very sensitive to heat. I think the frosting might be a product of heat and the "cleaner" reacting on the surface.
I tried baby shampoo and after 24 minutes in the ultrasonic cleaner, it stayed cool. Its a degreaser but its very genital compared to isopropyl or the chemicals in dish washing soap. It also left very little frost behind. I also have some Bestine I use to clean up drawings and models. It also works well but like you said, it turns the model white. I don't know what it does to it's structural integrity but I do know isopropyl and Dawn dry the part out making it very brittle.
So I'm running a test right now. I cleaned and primed 3 of the exact same trucks printed the exact same way. One cleaned with Bestine, one with isopropyl and one with baby shampoo. I got to say, the baby shampoo seems to be taking the primer the best so far. I have to let it dry overnight to make sure the primer drys and adheres to all 3 treated surfaces. I'll post the results and images tomorrow.