Absolutely... read this articles...interesting ideas on black hat: http://www.allthingssem.com/why-does-black-hat-seo-work/
There's also another type of SEO - Asshat SEO, which is the most common type. This type entails completely focusing on keywords completely ignoring any sense of meaning, logic and quality, which produces utter gibberish useless to humanity of any sort, unless there are people who like to commit slow brain suicide by reading such articles.