It's more about getting the mentions/rankings up... the way I understand it, the more mentions of a site there are when web indexing spiders crawl over a site, the higher ranked a site becomes in searches. If they catch some individual clickers eye from all the spam, that's likely considered gravy but not the main point of doing this garbage.
I would suggest the titles of this thread/responses have the garbage spam site edited out so you're not giving them free advertising by the way. ;)