I'm not sure I'm following. Check for what? How relevant a link is?

I think common sense can tell you if another site or page is relevant to yours. If it's on the same or a similar topic to your site it's relevant. That's why I suggest thinking of the link in terms of people. If you sell hiking boots then a site about hiking trails is relevant. Someone on a site with maps of hiking trails would likely be interested in hiking boots at some point or another.

Is that what you mean or are you asking something else?

Nope that was it.

My dear,

quality back link means link from gud site that have rich content and high PR.
page not be a link farm.

I think authority matters when evaluating a "quality" link. And, do some trackbacks when blogging.

Good luck.

Good pr, quality content and increase traffic