A website can be considered as spam if it has scraped content. Scraped contents are those stolen from other source either through copy-paste or the use of software. Wikipedia is one of the common source of these scraped content. If your website contains too many keywords or keyword phrases, then it can be considered spam too. The keywords should be placed in the content in a most natural way and avoid too many repetitions too. Hidden text is also another form of spamming. Texts are usually of the same color with the background, these invisible words are usually keywords.