How about "Risky SEO techniques" instead of "spam"?
IMO- Anyone developing a web directory nowdays is doing so in order to market to SEO's and webmasters. The common web user isn't going to use any of these directories unless the directory has a specific narrow focus.
People that say their directories are going to drive traffic are, for the most part, full of it! Even DMOZ doesn't send traffic to web sites. Yahoo! does because their listings appear in the SERP's.