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And it wouldn't make sense for these 404s to hurt your site since they originate from other domains.
I'd understood the OP was in control of both the originating and destination sites.
Websites do change their mind, even when they say "Gone" and Google doesn't want to miss any active URLs.
...sites with lots of broken links suffer some sort of negative when it comes to rankings in Google.
it is a long time we're linking you from banned websites and at last we have been able to make you disappear from the 1st page. Something worse is going to hit you!
In my opinion, rankings may be affected only if your internal links points to 404 pages.
If external links point to 404 pages should not be a problem at all, you cannot control this.
[edited by: tedster at 5:47 pm (utc) on Nov 2, 2011]
[edit reason] no personal URLs please [/edit]