I've had them open up Media Mail packages right in front of me when I was the sender handing them to the clerk at the PO. Luckily I was shipping actual books, but it was pretty annoying to watch them rifle through my careful packaging like I was a suspected drug smuggler. I definitely wouldn't want them handling comics I just sold.

I've also gotten a couple of grumblings from buyers that their books had been opened somewhere along the way and resealed with an inspection note inside. If it had been comics, they'd be forced to pay the difference in postage.

I'm sure there'll be people that say they've gamed it 1,000 times without a problem but it's just not worth the potential hassle to me.