As long as they are not spam type links from link farms or paid links that Google has logged it will bring no harm. Lets face it how many unrelated sites are on this forum that have sig links? Whats that telling you
Yes I agree with this. You have focus to get backlinks that really relevant to your sites. Don't push your effort to get backlinks from irrelevant sites because the result is not equal.
Fast Blog Finder Concerning backlinks, 1. Is it not bad if it is nofollow links? 2. If the anchor text is not appropriate, like a username, how does it influence pr or serp?
For answer number 1. I think that it doesn't hurt your blog, it just shows that you are getting backlinks naturally.
It's all about pr value. And it doesn't matter if it isn't related. A link is a link. You may not get much traffic if the subject isn't related, but if you're only building links, it doesn't matter