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I briefly had a forum on one of my sites, but after getting inundated with spam I decided to remove it for the time being. During the brief time it was up, most of the spammers were stopped from registering, but a few managed to get through and posted tons of links to their prescription drug sites. These posts were deleted almost instantly, but the spammers also created DoFollow backlinks on high authority community sites like ning. The forum posts they linked to were deleted immediately, so the links never went anywhere and the forum has been deleted entirely for a few months now. When clicked, the spam backlinks now bring someone to a "Sorry, that page doesn’t exist" page on my site. My site suffered a bit in the last Panda update and it made me look through my backlink profile, finding lots of these links - even though the pages on my site are long gone, could these links be hurting my site? Can a DoFollow link to a site help or hurt the main domain, even if the actual page it's linking to is deleted?