What's so bad abut spamming and cloaking?
Basically, any search optimisation technique that tries to mislead the search engines into giving a site a higher listing than it would otherwise merit, is not only unethical but can have catastrophic results. Two examples are cloaking, which involves submitting one page to the search engines and another to the users and spamdexing, which is multiple submissions of the same site. The search engines have publicly stated their commitment to stamping these practices out and anyone caught using them risks having their pages banned or blacklisted.
