On older books I always check the pages for anything missing. Whether it’s making sure all the pages are there and no cutouts. Along with page quality, staples not rusty and firmly attached, tears, etc.
Back in the day when you got your book signed, it got signed on the inside. So I also check for signatures as well as any famous people in letter columns.
On newer or lower priced books I’m nowhere near as thorough. I’ll make sure it’s got a digital copy if applicable and a real quick cursory glance at a few pages.
I guess I just expect all the pages to be in a newer book and it seems quite a few of us cut corners when it comes to checking. I feel like there’s a greater chance of me doing damage to check the page count than there is for a book actually missing pages.
I used to be much more thorough with all my books for a silly reason as well. As a kid and teenager it’s where I hid my cash. No one touched my books so it was the perfect spot. So I figured maybe other people did the same. Never did find any cash in comics though.
I just remembered and I just burnt down a tree so I’m gabby. About a year ago got some newsstand Captain America comics from a guy in California and there was some cannabis inside one.