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What do you mean, "legitimate companies"? You seem to have misunderstood the difference between an advertising agency and a SEO company. What you're describing is what advertising agencies do, SEO companies are spammers that sell access to their spamming tools. It's similar to the difference between an agency practicing law and having them send a cease-and-desist, and buying a DDoS. Not that I'm particularly fond of…
A plastic surgeon is a legitimate business. How on earth would a business like that promote its site and gain visitors? By paying exuberant fees on keyword auctions on AdWords? It's way more affordable to just pay a PR firm, or a SEO company to publish an advertorial on a news site. And no, not all companies that sell SEO are spammers. Grow up, please. Some of you guys need to get your heads out of your butts and rea…
Email spam is cheaper than news paper adverts, does that make it "legitimate"? Because that seems to be your argument here.