[tryp4vps]

No it won't hurt the site rankings. That's the beauty of this kind of techniques. Now that would happen if we use the site url or site name like post4vps.com. But we only use a word. So we won't get direct SEO benefit from this either. But this will build the authority of the site since Google Bot see the keyword in related web hosting websites. Since it's just a random keyword in comments it won't help those site since those sites are not optimized for that keywords. Even lets say Google rank those pages still it will help us since those sites will be promoting the Post4VPS brand involuntarily.....

Good points. And thanks for the top-quality answer.

If I understand your answer correctly, there is still a small risk Google may rank those pages for the keyword 'Post4VPS'.

Yes it will still help our Post4VPS brand, but when people wondering what is 'Post4VPS' and cannot find our forum in the first page of Google search for that keyword, then they may just give up.

So I think we better run this SEO campaign in a controlled way. For example just doing it on no more than certain number of pages per month.