I've got a list of about 60 spots I like to check for sleeks (not including the generic here). Some of those are unconfirmed but most of them I believe are valid. Also, not to get into the "woe is me" scenario here, but with my current char I have checked just about every single one twice over and haven't found a single sleek. Plus have done a lot of aimless wandering with detect artifact up. Ugh.