The business of search engine optimization is infested with sharks: scammers, swindlers, spammers and fraud artists. They are the Bad Guys of the Internet, and so like the Bad Guys in the old cowboy movies, we say they wear Black Hats. You could tell the good guys in the cowboy movies because they wore White Hats.
Black hat SEO is very different to what we have discussed. They consider any method that boosts ranking to be lagitimate and the only "wrong" is to be "too aggressive" and get kicked out of the listings. They will tell you that you can not spam the search engines whent he truth is tht all junk content of no value that fills every available space is spam.
Black hat methods can include using scripts to trick the engines, scripts to place links and social engineering to manipulate owners of sites. If you have ever seen a blog that has 978 comments talking about penis enlargers then you have seen the damage that black hat SEOs can do. That commnt spam was palced by a script and the aim was to manipulate the search engines to send traffic to the script owner.
Black hat SEOs care little for the expirence of the visitor beyond the statistical probablity that they will purchase something. Any method that can used to boost ranking is considered lagitimate so long as it is hard to trace to the black hat or unlikely to backfire. A black hat will also have some fairly self serving justifications of his actions side stepping the issues of who get's hurt in the process.
If you are interested in black hat methods then you should leave this site now as the specifics will not be covered. I have no desire to reduce the overall quality of search engine results just to help someone grab a few more coins. I just don't work that way.