Biggest black hat mistake is thinking the search engines are there to help you rank.
Idiots who simply copy what search engine reps say and propagate that aren't SEO's, they're simply accessories to the search engine's press release department (99% of gurus).
If you want to make $$$ you gotta defeat the search engine at its own game. You gotta rank a site with 100% Latin gibberish like some folks did last year, you gotta defeat the search engine at its own game.
Everything else is bullshit.
That's the one thing black hats should learn. If you do like 99% gurus say, you'll be chasing your own tail.