yes, but the hamful backlinks now can be removed via webmaster tools
Yes negative seo is really true and it is used in the terms of doing black hat seo. Although it still has existence after recent updates of google. Negative seo means all you do in in-appropriate way to just to get your keywords ranking. These includes keywords stuffing, low quality content, link backs from link farms and various other methods.
It does exist from the very first time internet is alive, though it is true, be careful with it, it can bite you back a hundred folds.
does it exist?
