As a collector of vintage paper items (including quite a number of old comics, going back to the early-1940s), there can be quite a difference in paper quality, depending on what kind of environment they were stored. I’ve seen and owned a few examples which have amazing fresh, off-white paper, with no yellowing or browning. Rare, but if some old comic was nicely tucked away in a stack of mags, in between two larger magazines (like old Saturday Evening Posts), in the attic of a dry, western or mid-western home’s attic for decades... the paper will retain a surprising whiteness and like-new flexibility. The acids within the paper haven’t had a chance to degrade it.
On the other hand, I’ve seen examples of comic books that seem outwardly untouched and otherwise in ‘new’ condition... but they were stored in attics in hot, humid locales, and the pages will be brown and brittle. Even breaking apart upon touch.
Personally, I've never seen it.
I own Mad magazine from #1 to the present.
You can actually see the changes.
1952, a very yellow-brown. By the 1970s still a tinge of yellow, even though I bought these off the stand.
And how brittle.
Some of my '60s paperbacks cannot be read, because they just crumble. Plus the backing falls apart and you're left with mere pages in your hand.
Not saying you aren't an expert, just never seen such a specimen.
Best of luck to the buyer, though.