Hmm I did not know of this, but if you search Black Hat you get 49,300,000 results, but if you search Hat Black 65,300,000 results. Why is that? Isn't it the same search terms?
Of course not, i dont really know how to explain this to you, but any keyphrase that you will search and then search the opposite, you will get different results. Especialy with common words like "Black" and "Hat"
Both keyword are compose of 2 words. The "Black hat" is popular as an SEO technique and it's already in their database while "Hat Black" is not so popular meaning the results might come from the 2 words which is the "Hat" and the "Black".
hat, black, blacks, hats, SEO, techniques , spammer lets assume, how search engine react ? { after 5ive days } though you should check these too with "black hat seo" and "hat black seo"