I run a webmaster forum and we have similar problems, mainly with Indian SEO companies. They are constantly spamming. Just as you said, these companies seem to have questionable ethics and very lazy practices. These are probably the same companies that send out spam saying they can increase your search rankings. Right, by posting spam on forums and “dofollow blogs”.

(I came across your site after going through some old emails. You contacted me ages ago with some encouragement for my blog. Thanks a lot!)