How to select as well as target those all important keywords when Search Engine Optimizing (SEO) your website.
Googler, Matt Cutts publicly outed a spammer using a text box to keyword stuff his webpages full of keywords. Whether or not Google can detect the gimmick of using tiny text boxes as a means of lamely hiding text on a webpage is totally besides the point. Adding hundreds of different words to a webpage, whether visible or invisible, would only decrease the keyword density of each of your keywords close to zero.
Amazon.com has 1.8+ million webpages each of which is automatically generated every time a new product is added. The only interesting, or fully developed, webpages to be found on Amazon.com are those for the same popular items being offered by off-line retailers. The long tail marketing tactics of Amazon.com apply only to their obscure hard to get items, most of whose corresponding webpages are quite undeveloped and empty. To try to apply the same long tail webpage development concept to the average site that contains only hand written content is an absurdity that perpetuates a fallacy of unreasonable expectations on the part of naive website operators.
Google favors keyword density over keyword repetition. So, there is never a need to write really big pages where a keyword is repeated hundreds of different times.