Mostly the markings will be correct but I've seen some people mentioning bad markings.
Another thing is having sometimes a capacitor value way out of the 5% or 10% tolerance.
Even worse, I just found a brand new 150n cap that had a reading of .... 0.000, in my first builds, this would have been mounted on the board without any verification, and would have meant troubleshooting. I'm on the L4 board, the last thing I want is a value error.