At present spotted, clouded, or milk blurs on the
ASE, especially the Proofs, are avoided by the vast majority of set builders.
Anyone who has gotten excited about getting an
ASE, especially a proof, at a GREAT price, probably didn't look long enough to see a cloud or spotting.
This has nothing to do with the grade of the coin when it was graded. That spotting, clouding, and toning occurred almost exclusively after encapsulation.
Everyone, myself included, who has built or worked on an
ASE set of one type or another has received a "bad" coin they didn't expect.
Trying to sell "bad" coins by honestly noting the problem, rather than surprising a bidder who did not look close enough, will result in significantly lower bids.
Being cheesy and just putting a bad coins photos up with no mention of the problem (or "accidentally putting up blurry photos) will result in a lot of returns and bad feedback.