This is just a new twist on the philosopy of...If you can't beat them, join them. I spend a bunch of time and money on SEO efforts and for the most part they pay off reasonably well in rankings, but it seem that more and more, I am getting beaten out of the top spots by sites getting backlinks from comment spam. In one example, a competing website to mine went online on Nov 30, 2010. They currently have nearly 1,200 backlinks to their site as reported by yahoo site explorer. All backlinks are comment spam. No articles with links, none from forum profile postings, no web 2.0 pages, no videos, nothing else. And they are #1 in the SERPs for that keyword. Another interesting thing is that in every case that I checked, all links are marked nofollow. So I'm also starting to doubt the validity of that tag as well. Any comments?
I think alot hinges on that term you used; validity. I can not make recommendations because I do not know your niche, but I will say that some successes in SE rankings will be a matter of who you know, not what you know, similar to politics.
Spam Blog commenting will eventually get a site moved to the last page of the serps for those keywords. In this case, I don't think you should join them if you can't beat them... Because you too will reap the same consequences if you start manipulating (SPAMMING) the Search Engines to get a hire ranking. Blog commenting can go a long way, when done correctly, but I would concentrate more on branding yourself in your niche and forget about SEO. Well, not forget about SEO completely, because just about everything you do to a site is technically SEO, right? Brand yourself and your content, be the authority on what you talk about..<--------- Everything falls into place when you can accomplish that! The name of the game is to brand your name or a website to be absolutely synonymous with trust concerning various subjects and niches. Take your time, right some articles, a couple of press release, get yourself on Facebook, Myspace, Twitter, A few social bookmarks here and there, A video or 3 on some of the major Video sources... This stuff is some serious business, but those who cheat, will eventually get caught... Stay away, and practice "White Hat" techniques...
I wouldn't jump to the conclusion that the spammy links are what is ranking them. It's possible that they have created a couple of backlinks from high .edu or .gov sites somehow and either you didn't notice them in siteexplorer or they aren't there but Google has picked them up. Your idea isn't fully backed up, you would need access to their webmaster tools to truly know how their backlinks come in.