Is it a good idea to comment on blogs not related to your niche?

Are you interested to get traffic directly from these comments, or do you use them for SEO? If the goal is direct trafic, I think it's best to comment on related blogs only.

But if you want to build backlinks, any backlink has some SEO value, even if a backlink from a non-related blog will likely have less SEO value. The way I see it, it's a matter of optimizing the use of your time.

Ya its true. If you really want to get some backlinks to your site and want some direct traffic then use relevant links its great.

Your actually defeating the object attracting visitors to non-topic related blog comments . . . regardless of link advantages or improved ranking.

Much better to have fewer quality visitors who have a genuine interest in the article/blog than 'a few heavy showers but the crops still don't grow'. . . . . I like that expression, and just made it up myself by the way

Sometimes less is more.

It's not a big deal, but to be honest I don't altogether agree with most of the responses above. (I do agree completely with Sharon, immediately above.)

Call me a skepchick but I think that pleas for "variety" sometimes conceal a compromise on quality (I'm talking about backlink quality, not comment/content quality).

There's no harm in commenting on blogs that aren't "up your street", but one has to ask oneself whether it's a valuable use of one's time.

For me, most of the time, it just isn't: it's time I could be using writing a new article, writing a new autoresponder email, working on a website, posting in the forum or painting my toenails, all of which are frankly more significant to me than non-context-relevant backlinks.

The idea that "a backlink is a backlink" (and its obvious implication that they're all more or less the same) is - to me - so diametrically opposed to all notions of common sense, practicality and sensible SEO that I'm not even going to go there.

The discrepancy in link-juice value, for my business, between backlinks from relevant sites and any others is so overwhelming that, although I agree there's no downside at all, I'm just not interested in non-context-relevant backlinks - not to the extent of looking for them and posting them, anyway. The idea that Google somehow prefers "a mixture of backlinks" is - to me - just an intellectually lazy, see-through attempt to justify spending your time/effort on poor quality/relevance backlinking. Others' mileage may vary, but in my business, that doesn't help to pay money in to the bank. (And to be honest, we can all see for ourselves, from analysing the SEO-quality of the top-ranked sites in many SERP's results, that it's nonsense).

The only real reason for commenting on off-topic blogs is that you have nothing better to do. In which case, fine - do it: there's no downside. But don't expect to benefit from it.

Well, go for it! A dofollow link will not harm you in any way, variety is good when it comes to link building. This is how you get to become an authority website.

I would stand in line with Alexa, a time effective approach to achieving a grater goal, with the exception of course to the painting of one's toe nails, as I find no value in such a mindless daunting task.

I did, however, find value in the time she spent in her post as myself, I am not allowing sufficient time to provide a quality post that will gather additional attention. I personally took the time to look at her signature file, simply because she took the time to post an engaging comment.

If you did the same it would give references to taking the same approach, and not simply think of your efforts as a backlink mission, but rather to gain an audiance.

Sufficiently, I do not put a lot of value in a self promoted back links having a lot of value, and based on how much time I spent to get one link. I am not sure it was worth it.

You're proving my point I just made above

Not at all. Don't be overly paranoid.