I haven't had any issues with SP3 quality control (knock on wood) but the Type Cover 3 quality control is TERRIBLE.
There was a "pimple" on my first one which made the cover look uneven. It was noticeable from any angle, and if you touched it it felt really sharp like there was a nail or something sticking out of it.
MS Store exchanged it with no questions asked, but I opened the replacement in the store just to make sure there were no problems with the new one. I am glad I did, because the felt was torn in the corner on the brand new one and the circuit board was sticking out!
I showed them at the store and they were stunned. I apologized for making them open so many. They opened a third and it's is (almost perfect). Only gripe is that the touchpad is a little uneven at the top edge (left side is lower than the right side) but it's barely noticeable.