have scales fall from (one's) eyes
To suddenly be able to see a situation clearly and accurately. I used to be so in love with Andrew, but now that we've broken up, I've had scales fall from my eyes, and I can see how oafish he truly is! Once you start working somewhere new, it doesn't take long until you have the scales fall from your eyes, and you can see all of the problems of your "perfect" new job.