It doesn't mean that you are giving junk to the viewers but it means the replication of content. In SEO some become so furious of getting backlinks for which they will use the same content in other PR websites. This method will not provide backlink instead the crawler will consider it as a copy content and ignore the website totally.
In the wish of reaching top charts some people used to stuff keywords everywhere in the website. This is not a correct technique maximum you can use 5 to 6 keywords per page. Do some keyword research for best keywords.
Lack of Sitemap:
The website which lacks the sitemap will never be placed in the search results. Sitemaps are like eyes for search engine crawlers to navigate through the website. Make your website sitemap friendly.
Interlinking to the website is advantageous in some extent only when more interlinks are produced unnecessarily there is a huge chance of getting ignored.
Last but not the least every webpage needs killer content where viewers should like to spend time reading. If a webpage with high back links, perfect on-page optimization and sitemap is provided with a poor content then that website will never get authentic visitors and obviously get banned.