Actually the beauty of plastic frames is their ease of cleaning and reuse.  I had a hive die off this summer and the Pierco frames were the only ones I could save
because of wax moth damage.  Merely scrape off all damaged or moldy comb with a hive tool and throw that in the fire.  The scraped frames can be given back to
the bees, who will clean off all mold, bits of debris, etc.,  and rebuild perfectly good comb on the plastic midribs.  Don't try boiling, soap, or anything like that - it
is not necessary.  The only thing to be concerned about is AFB.  If the colony died of that, I would discard the frames.

Ted Fischer
Dexter, Michigan USA