Depending on what kind of spam/scam it is, for scammers of the kind "you have inherited $$$ from your relative in Nigeria" I have read that the scammers actually deliberately write the text badly, with errors etc. as they want to deal with people who are gullible enough to see past that, and deter the smarter people in the first place. I don't really know if that is true, but it does make some sense, if you're running that kind of scam you are looking to find real idiots (to be clear, all these scams and spams is and should be illegal and the perpetrators prosecuted, but a bit of common sense knocks out nearly all of it).
Perhaps in this case, with general spam, people are just running bots on any websites/forums they can find that have simple enough sign up processes that it can be scripted (no complex CAPTCHA etc.) and since it costs essentially zero to spam another forum they don't care if the forum is relevant to their spam.
I suppose really if you're an educated Korean who speaks good English and could do that kind of intelligent work, you would have a real job with a salary rather than trying to earn some click-through commission on spam links.
