It could be profaned by the high priest going out of it, while the anointing oil was upon him, for the dead; (Leviticus 21:12) by a man's negotiating to purify himself; Numbers 17:20 see Numbers 19:20. All the chief of the priests and of the people polluted it by transgressing very much after all the abominations of the heathen; 2 Chronicles 36:14. "Surely, because thou hast defiled My Sanctuary with all thy detestable things, and with all thine abominations (idolatry), therefore will I diminish thee." Ezekiel 5:11. Moreover this they have done unto Me; they have defiled My Sanctuary in the same day, and have profaned My Sabbaths: for when they had slain their children to their idols, then they came the same day into My Sanctuary to profane it; Ezekiel 33:38,39. "Her priests have polluted the Sanctuary; they have done violence to the law." Zephaniah 3:4.
Antiochus polluted it by offering swine's upon its altar, 1 Maccabees 1:20-24. From these texts we can clearly see, that it was moral rather than physical uncleanness that defiled the Sanctuary in the sight of the Lord. True, it did become physically unclean, but that uncleanness had to be removed before the atonement was made by which it was reconciled or cleansed.
See 2 Chronicles 29. And that, we have seen was the law of cleansing, Leviticus, chapters 12 to 15; the object must be made visibly clean, so to speak, so that we would call it clean , to prepare it for its real cleansing with blood. Now no one supposes that New Jerusalem is unclean or ever has been, as its type was when overrun, desecrated and desolated by Syrian, Chaldean or Roman soldiery, or trode by wicked priests.
Even if it were, the removing of such defilement would not be the cleansing it was to undergo at the end of the 2300 days.