scratch A and you'll find B
scratch (something) and you'll find (something else)
If you investigate a certain type of person, organization, or thing closely, you will almost certainly find another, often contrary characterization or trait as well. There is a misbelief in popular culture that if you scratch a devout Catholic, you'll find a radical fundamentalist. My father always told me, "Scratch a successful business, and you'll find a hive of corruption."