There has been a lot of debate out there on the black hat and white hat side of things. One thing you will rarely find is a black hat tell on an other black hat. However, there are some white hat firms that are starting to add "spam reporting" to their SEO package. A thread over at HighRankings named Spam Reporting 2, Obligations and Issues details some of Scottie Claiborne's issues with spam results:
1) Relevant spam is often not removed 2) Algorithmic penalties do exist 3) Some sites do well despite spam techniques, but probably not because of them
It is going to make for a very interesting thread.