Like I wrote, that's a different matter. And certainly not the one expressed by the original poster, who lamented that boogers and blood couldn't be removed without being considered restoration.
I haven't seen anybody on the Boards complaining about getting purple labels for dry cleaning, and plenty of folks here C+P when they submit. This is pure speculation on my part, but it sounds like such books just weren't cleaned using proper techniques, which wouldn't surprise me given the proliferation of YouTube pressing "experts" and their followers who think they know more than they do.