Pretty much the same way. Sometimes they are happy to see something other than a glossy picture, sometimes they want to look at it or read it (thus the invention of the window bag). And sometimes they are just in signing mode and don't really care.
A couple of examples:
Ron Perlman - Richie sent me to get a couple of books signed by him at Chicago. He spelled his name wrong on his window bags. Perlman is a super nice guy, but he throws the rough and gruff schtick around some. I get up there and he says "WTF, all these Hellboy books and my name is spelled wrong every time!!!" I told him about Richie, and got my picture taken with me holding the books and Perlman pointing at it with a pissed look on his face. He may or may not have given Rich the finger. He had the whole staff cracking up.
Aliens signing: I CAWed an Aliens signing in Indianapolis for Triston in Sept. 2012. There were lots of really nice books, including a couple of Rare Sigourney Weaver Night variants from Celebrity Authentics. I was up all night prepping stuff. Chris Caira had sent a couple of books, and had gotten a book from Richie sort of on a whim. It was not window bagged or anything. I had to pull it out of the stupid bag for all of them.
Rico Rossy was the last person to sign it (It was really nice by the way. Aliens #1 v.2) He sees it and freaks out! Grabs it out of my hand and rolls the cover back and starts reading it trying to find out if his character is in it. I was positive he had butchered it, by the time he was done. It still came back 9.8.
Mostly they are great, but even when they are not (Carrie Fisher, Anthony Daniels, Jackson Bostwick) they at least make for funny stories.