Rebbe Meir of Premishlan once stepped into a dirty shul and called out:
מה־נורא המקום הזה! אין זה כי אם־בית אלהים וזה שער השמים.
The Chassidim thought he meant something kabbalistic or Chassidic. But no.
The Rebbe explained: If this was your private home you would never let it look like this!