Field of Dreams reference, right? Right!
(Tatakeba hokori ga deru; “If you strike it, dust will come out.”)
No matter how much you smooth over the surface of something and make it presentable, closer inspection will reveal flaws; no matter how polished a person’s surface is, looking closer at their dealings or their past will reveal improprieties. The image is of a surface that looks clean and polished, but which yields dust when struck. By extension, the idea that every human has weaknesses and failings; we’re all only human. Note that this saying only talks about negative features; it can’t be used in reference to hidden talents or good points.
We begin with the verb 叩く (tataku) in its subjunctive form, followed by a verb phrase comprising a noun – 埃 (hokori), “dust,” and a verb – 出る (deru), “to come out,” in sentence-final form. Although this noun is attached to the subject-marker particle が (ga), it is only the grammatical “subject” of the verb phrase; the sentence as a whole has an indeterminate human actor as its unspoken subject. In English we express this subject as the indeterminate “you” or, if you’re feeling fancy, as “one.”
This saying has a number of synonyms, including a version in which the final verb is replaced with 立つ (tatsu), “to rise.”
(“Donna seijika de mo tatakeba hokori ga deru to iu ga, aitsu wa toritsukurotta hyoumen sura kaketeiru. Tada no hokori no katamari ga koudou shiteiru to ittara ii ka na.”)
[“They say any politician will have drawbacks if you look close enough, but that guy lacks even a polished surface image – you could say he’s just a walking pile of drawbacks.”]