We may discuss a lot whether SEO spam is right, is moral or have not to be used. The fact is that these techniques are often the most powerful trick to increase your ranking; if your are competing for a single competitive word and the twentieth position is not enough the only alternative to SEO spam is buying the position from the search engine.
Anyway these techniques are forbidden, if you are caught using them, although you do not use them with unscrupulous ways, you may be penalized or banned. Actually guilty websites are not often penalized. It depends on the nature of the 'offence' and in the importance of the website; the final goal of a search engine is to present the relevant content, if your company is famous and the website has lot of visitors, obviously your website will never banned from the index or lot of searchers will start doing searches with others search engines. But if your website is about animals and you use SEO spam to achieve a good ranking in the search term "car", it is likely that sooner or later you will be banned.
While it is true that search engines are very poor at spotting unwanted techniques, they mainly rely on people reporting them, it is definitely better that if you are a beginner in SEO spam, you buy a new domain and experiment with it first; after gathering some confidence and experience, you could expand your techniques to your serious website.