I've been doing active (and oftentimes aggressive) link building for a few years now, I guarantee that this method is safe. I do agree that a judgement call needs to be made when choosing to comment on a blog post to make sure that the quality of the post and site is up to standards.
Honestly, if someone asked me how to get a lot of links to a site, I would not tell this method. If you want a lot of low quality links, you need to be automating heavily. This strategy isn't meant for low quality links.
Just because there's software out there to automate blog commenting doesn't make all blog comments bad. A good comment on a good popular post is gold.
If you're building a business in the SEO industry, you probably shouldn't throw around guarantees like that.
I think that this method is probably safe, especially if you the target site has a decent number of higher quality links. Still, it does come with some risk.
It wasn't long ago that Matt Cutts told us that duplicate content was ok and that Google would find the canonical version on its own. Then Panda came along. It was a widely held perception that incoming links couldn't hurt you. Now we know that they can.
Google's algorithm is a moving target, and it only seems that they will get more aggressive on discounting or even penalizing links that aren't given editorially.
Honestly, if someone asked me how to get a lot of links to a site, I would not tell this method. If you want a lot of low quality links, you need to be automating heavily. This strategy isn't meant for low quality links.
Just because there's software out there to automate blog commenting doesn't make all blog comments bad. A good comment on a good popular post is gold.