...or did you? Here's the deal: first, 50,000 words is not a novel, unless you're writing middle grade. You're going to have to beef it up to 60,000 words—minimum—and would probably be better off getting it into the 75,000 – 90,000-word range. Over 100,000 is probably pushing it.
Second, even if you have 75,000 – 90,000 words, that is not necessarily a novel. Unless you've got all the necessary parts in place and working, it's just a pile of words.
Third, no one in his or her right mind should be submitting a manuscript to agents if it isn't the absolute best piece of writing he or she is capable of. If that's true of whatever you churned out in a month without editing, you probably shouldn't be writing. Period.
Last, it seems that a lot of people are missing the point of NaNoWriMo altogether. Despite Chris Baty's invitation to "write laughably awful yet lengthy prose together," a lot of folks are getting really amped up about having finally written a piece of fiction of substantial length and are more concerned about FINALLY BECOMING AUTHORS ZOMG than about having fun writing crap, which is what the contest is really about. If even one sentence of whatever you concoct in the spirit of NaNoWriMo leads you into a publishable novel somewhere down the road (with substantial editing and revision, of course), you should count yourself lucky.
Think of it this way. Over 119,000 people signed up in 2008. If even one in ten of those people thought they could pass off what they'd written that November as a finished novel and tried querying agents, that's eleven thousand nine hundred queries (thanks to Marshall in the comments for correcting my mega-sweet math skills), assuming each person only wrote one. And who only queries once? No one. Especially not people who think they've got a representation-ready novel after a month of fly-by-the-seat-of-your-pants writing. As you can imagine, it gets kind of annoying when a small minority of NaNoWriMo-ers believes they're done at 11:59 PM on November 30th and starts the Query Machine going at full tilt at 12:01 AM on December 1st. It's especially annoying because the holiday season is the industry's busiest time, meaning agents and editors are already swamped and really don't want to have to deal with an influx of terrible writing from writers who may or may not understand anything about the book publishing industry.
So, in summary:
· If you're participating in NaNoWriMo, have fun!
· Don't send your 50,000-word MS—or even 90,000-word revision—to agents until and unless it is the strongest piece of writing you could possibly forge in the fires of Mount... Your Imagination.
Tomorrow: Laura! Round-up!