My library has a sign by the entrance that says “No food or drinks please. Thank you for your co-operation”. Then, just a litte past the area where we drop off books, there is a coffee machine where we can pop $1 in for a nasty tasting cup of coffee. 
Also, there are constantly people taking in food to eat. A candy bar here, and a sandwich there. What’s really annoying about that is how their paper crinkles. And it’s not like it’s one crinkle and then it’s over. It’s more of a crinkle… crinkle … crinkle crinkle crinkle SMACK as the person with the candy bar gulps down his/her last bite and squishes the wrapper into a ball and leaves it on the table/floor/whatever.
I’d like to also point out that not only do food and drinks sort out the computers when spilled or crumbs seep into a crack. But if there were spills and crumbs lying around, it attracts all sorts of bugs and other creepy things. I don’t remember what it’s called, but there is a type of bug/worm that eats the glue that holds the books together. And after a while of this bug/worm eating it, it would fall apart and you’ve got yourself a book with a couple of missing pages and therefore useless.
Another thing, back in high school, we had two “real” librarians in our library. The rest were student volunteers. They basically helped check books in and out, reshelf things, and took people’s money for the fines. They also get special treatment from the “real” librarians. Not the kind that’s like “Let me hold this book for you before the others, just because you’re helping us out.” It was more of a contraticting special treatment.
One time during lunch, about three or four of us headed over to the library to study for an exam coming up. Two of my friends pulled out their lunches and started munching away. We were sitting down in the back room, with the group tables and all, away from the books (except our own) and the computers (which were pieces of crap anyway). The librarian comes wandering in, and tells Friend A she has to put her sandwich away immediately, even though she had about three bites left. Then, he turned towards Friend B and tell her that it’s okay that she’s eating her muffin because she works here. I was like "WTF?!
" But I was just a lowly high school student and didn’t want to start a debate on how much of an asshole he was being, especially he since I wanted to get studying on my exam.
It boggled my mind, though. He’d go on and on for hours about how the sugar in the food ruins the books, and even it wasn’t spilled directly on them, the sugar would attract ants, and ruin the books, and all that. No food or drinks in the library unless it’s water seems fair to me. So then, what the hell did he think he was doing, telling one person she couldn’t have food, and then telling another that she could because she works there?! If he did indeed wanted to discourge food and drinks, it seems like a better idea would be to enforce the no drink/food on everyone, so that the volunteers would set a good example. It still pisses me off to this very day!!
Sorry about this long post. I seem to have trouble keeping things short and simple.