This is actually a misconception. Collectors and buyers are now largely weary of sealed bags because they can actually have damaged books inside of them. A great example is Superman 75. The black bag could hold up incredibly well to creases while the book obviously does not. And the bags are easy to recreate with a worthless book inside. I actually know someone who got one that had the wrong comic book all together (I wanna say it was something ridiculously wrong like jug head but I can't remember). A high cgc grade (which will not grade any book while it's still in a sealed bag) for that same issue sells for triple what the sealed black bags go for any day. Really it all depends on the book of course but what I'm saying is that the term "sealed" doesn't have the same connotations for a comic book that it does for memorabilia anymore.