I don't always read the foreword of a book, but when I do, I usually forget it.
There is one exception to an appropriately exceptional novel: Infinite Jest. The foreword (at least in my edition) was written by Dave Eggers. I don't remember everything but I remember his general point was that David Foster Wallace proved you could write high-brow literature and still include low-brow jokes. For example, there is an entire chapter in IJ about a fart.
Eggers comments on this because it fits his style of writing. While it might not be as high-brow as Wallace's (then again, whose writing is?), Eggers' work is a good example of well done postmodern literature. You can see this style prevalent in much of the work published by McSweeney's. You can see it in his Best American Nonrequired Reading series, even though he supposedly works with high school students to select submissions.
The most recent place I see this is in Grantland, perhaps the best writing on the internet. My favorite writer is Jason Concepcion. Not just because he answers all my Game of Thrones questions in his Ask the Maester column. His prose is brilliant, funny, and intellectual. In a Game of Thrones column, he refers to Mance Rayder as Colonel Kurtz. How many people got the Heart of Darkness reference? Or even the Apoclypse Now reference? I don't know, but I loved it.
All of these examples tell me one thing: comedy is smart. Humor often gets frowned upon because it's seen as not serious. Many of the rules of grammar and proper usage of words I only know because I devoured George Carlin books as an adolescent.
Sure, there is cheap comedy, which relies on swearing and getting kicked in the crotch. But good, quality humor comes from intelligent minds. Even if the jokes are sophomoric, you can be erudite and still appreciate them.
As Louis C.K. once said of a fart joke, "You don't have to be smart to laugh at it. But you have to be dumb not to."
