Don't forget it can happen during Night VFR too. I was climbing out along a coastline doing Night VFR, beautiful starry night. The ships out to sea were also sparkling as were the homesteads or whatever individual buildings were lit up on land.
As I climbed out between using the instruments, the light from the airport/town, and just generally being on top of it my perspective stayed "straight". I put my head down to note my departure time, do my fuel log etc. My head came up and suddenly my eyes/body was telling me something different to my instruments. I set attitude off the AH but my body was screaming this was wrong. What was worse was, what used to be a good reference outside had now changed to 360 degrees of blackness with star like sparkles in all directions. I suddenly was in perfect VFR with "sky" all around as far as I was concerned.
It took a while of focusing on the instruments and eventually my inner ear caught up and the next time I looked outside I again could tell the difference between the lights in the sky and on the ground.