I wonder if the vertical spit cooking method is what makes them so good. Good Al Pastor is slightly charred on the edges. The pineapple cooking on top adds a hint of sweetness.
I've tried a few recipes at home with various degrees of success, but never been able to replicate the real thing.
Here's the best one I've tried, though it takes a long time:
https://youtu.be/F7N3l6XGn-0