tedster - 5:28 pm on Feb 21, 2010 (gmt 0)
A few years ago Google changed the wording about whether competitors can hurt your rankings. Here's what they say at the moment:
Can competitors harm ranking?
There's almost nothing a competitor can do to harm your ranking or have your site removed from our index.
Note the addition of the word "almost". I guess Google doesn't want to worry people about those situations where a competitor's actions are not harmful, where Google catches what's going n and ignores it. When I'm analyzing backlinks, I do see a lot of attempts at competitive disruption that are a fail.
But, the change in wording is an admission that there are some things a competitor can do that might hurt your rankings. If I remember correctly, the change came along with the war on link buying.