Additionally, I know not all of the make money online "offers" really work despite the fact that they all claim they do.
I've been an IT professional for over 20 years and I've spent countless hours blocking spam. I've moderated and administrated several forums and I've banned, rebanned and IP banned many thousands of "members" (and many domains with SEO in them too) that really had zero interest in being part of the community but instead only care about spamming their backlinks regardless if they were relevant to the site or not. Some spammers try to hide their spam as questions or answers. As far as I'm concerned, even if the spam is relevant it's still spam if the "member" only cares about the link and has no interest in actually being part of the community. Blogs are no different.
So, are there ethics in marketing/advertising or is the only limit what they can get away with that works? I know that some people will reply and say "we don't spam" but I also know that some of those probably really do. Certainly, not everyone spams but is that the exception or the rule?