Last one; I really hadn't meant to spend my night doing this.
Thieves Guilds and Other Criminal Societies
The Thieves Guild is a common staple in fantasy novels. Terry Pratchett's Discworld books parody it; Scott Lynch's The Lies of Locke Lamora critiques it; and Steven Brust's Taltos novels examine a more modern Mafia-style version. What's good, bad, interesting, boring, otherwise worth talking about when it comes to this idea?