Quoted from google page below
Code:
http://support.google.com/webmasters/bin/answer.py?hl=en&answer=34444
So for those thinking you can scrapebox a competitor's url to punish it then you should stop this and save yourself some money.
They've been saying this for years.
"almost nothing". Why would they use the word 'almost'?
This is basically just their public response so there's not an outcry and panic. If even a large amount of people on a blackhat forum think you can't damage people's rankings, then imagine what the average seo thinks.
This is exactly how google wants it. They don't want panic and they don't want people investigating or attempting to attack other people's rankings.
Come on though. If this were the case you could just go and register a new domain, blast it to hell and have stable rankings. Anyone who's even done a bit of seo knows you'll dance about like a magical fairy at best, and at worst you'll just hit the sandbox.
If you couldn't damage your competitor's rankings then there would be no concept of a 'bad neighbourhood' in google.
It really amazes me how quickly people are to believe what google says. What company in history has been entirely truthful about things that will affect their bottom line?
Even when toyota had MAJOR faults in their cars that meant brake-failure, they STILL played it down. If they'd play down as something as serious as that, do you really think google isn't going to play down the fact you can blast your competitor's with bad links to damage their rankings?
It's all about the ratio of "good" to "bad". If a site is aged, has 1000's of diverse, authoritative/trusted backlinks from 1000's of unique domains, then there's very little you can do to damage their rankings by using backlinks.
If they have 100 backlinks and are maybe a year old, then yeah, you can do a lot of damage if you get them a couple of million shady backlinks in a week then backlink those backlinks with blog comments to get them indexed.
It's just completely pointless to do this. Who wants to sit attacking a dozen competitors? You're better off just launching more of your own sites and dominating page 1. If you knock 1 competitor off another will just appear, so it's futile.