Ten Controversial Search Engine Optimization Techniques

In this article I discuss ten controversial search engine optimization techniques that should be used with caution, or even avoided altogether.

1. Duplicate Pages,  In general, search engines ignore duplicate pages. In extreme cases, they may ban a site. 
2. Invisible Tex,  Search engines consider the use of text that is the same color as the background color as spam. So stay clear of using invisible text. 
3. Keywords In Comment Tags, Hardly any, if any, of the major search engines index comment tags, so don't waste time adding them for optimization purposes. 
4. Keywords In Hidden Value Tags, Keywords in hidden value tags are considered spam by all of the major search engines, so don't waste time with this practice. 
5. Keywords In Style Tags, Very few search engines index the content of .
6.  Link Farms And Link Exchange Programs, Search engines consider link farms and link exchange programs as spam, as they have only one purpose - to artificially inflate a site's link popularity, by exchanging links with other participants. Do not confuse link farms and link exchange programs with reciprocal linking. Reciprocal linking is the exchange of links with individual sites, and certainly an accepted technique for improving your site's link popularity.
7. Links Only Pages, I recommend adding text descriptions to link pages and site maps. Some search engines have been known to kick out links only pages.
8. Meta Refresh Tags, In general, meta refresh tags set for under 30 seconds are considered as spam by search engines. As such, most search engine optimizers use JavaScript redirects. Are you confused? I certainly am! So to be on the safe side, I suggest sticking with JavaScript redirects, until there is conclusive proof that search engines accept meta refresh tags.
9. Tiny Text, 
10.  Many of the major search engines consider tiny text (i.e. font size 1) as spam. Some use of tiny text is fine. Search engines don't like web pages that use a lot of tiny text. The reason is because some webmasters have used it to fool search engines by "hiding" dozens of keywords in a web page.
11. Cloaking, Cloaking is the practice of serving search engine optimized pages to search engine spiders, while at the same time serving un-optimized pages to site visitors.Cloaking is one of the most controversial strategies in search engine optimization. Major search engines publicly state that they consider all cloaking to be spam. However, many professional search engine optimizers have been using cloaking for years, with much success. Until there is conclusive proof that search engines do indeed ban sites that use cloaking, I suggest you take care if you decide to use cloaking.

Conclusion There are many controversial search engine optimization techniques. There are people who despise the use of certain techniques, such as cloaking. But the fact of the matter is that there are no right or wrong ways to optimize a web page. What might be considered as spam by one search engine may be accepted by another. What works today may be banned tomorrow. The art and science of marketing is about testing to see what works and what doesn't. I recommend taking the same approach with search engine optimization. After all, it is just another form of marketing.

Source : http://www.mikes-marketing-tools.com/marketing-tips/advanced-optimization.html