I've been pawing through the 2009 Writer's Market for literary agents and finding a great deal is out of date. Some agencies no longer accept my genres, perhaps because those specific agents have moved on. Some listings are not quite what the book suggests. One was merely a catalog page of links to other publishing agencies. Suspicious!
I've passed on a few just on the "feel" of the web page. Not the colors or the pictures, more how easy it was to find information, how much information they had available, if they had agent bios/pics, and of course what they said. Some were very sparse with the info and it was hard to find who represents what genre. One I found offers a lot more services than agent, which again raised my suspicious flag. Maybe they're legit, maybe not.
I found an agent I like, but she didn't specifically say "fantasy" in her reading list. I sent an e-mail and am waiting to see what I get back.