Why it wont score a 10/10?
From the Google blog,
From now on, when Google sees the attribute (rel="nofollow") on hyperlinks, those links won't get any credit when we rank websites in our search results. This isn't a negative vote for the site where the comment was posted; it's just a way to make sure that spammers get no benefit from abusing public areas like blog comments, trackbacks, and referrer lists.Now, this means that if I add rel=nofollow attribute in the links, then no one can just fool around and increase his website rankings and thereby has no reasons to spam! Right?
But what about those comment spams whose objective is nowhere linked to achieve higher website rankings/pageRanks but is to spread awareness about their 'product', which might be a blog or a brand. All this spam strives for is people visiting these URLs and taking note of their website. In this sort of a situation, I do not see rel=nofollow being of any use.