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."
See also: and, find, scratch

scratch ˌA and you’ll find ˈB

(used to speak about particular types of people in general) carefully consider or examine somebody/something and you will find that they are different from their outside appearance: Scratch a senator from Texas and you’ll find a cowboy.
See also: and, find, scratch