Here is a good example of which site is relevant "contextually/topically related" and which site is not relevent for
link exchange:
If your website is all about real estate/home improvement. Links from a "Automotive" page/site would not be "relevant" - not unless it came from a page/chunk of text that was realted/discussed your area of expertise.
Quality links are those from trusted/popular sites, and that occur "naturally".Things like links from a page listing links are not likely to be viewed as "trusted".(think of it like a menu, with a slip of paper listing a few extra food options - are you going to trust the core menu stuff, or that slip of hand written paper?)
