You get the key from %test_hash, and check if it exists as a key in the other hashes, but if it doesn't, you print out %test_hash value associated with the key. Maybe yoou were just trying to simplify your code for us, but it does suggest you're confusing keys and values.

Besides the mixed-precedence bolean operations, I mean ... I've been finding perlcritic useful in isolating tons of minor weaknesses in some ghastly code I'm bringing up to modern standards, I'll probably be using it more often in my routine development. Mixed-precedence booleans is just one of many things it warns about ... Be sure you have it on the harshest setting.