Matt Cutts talks about getting successful back links and how they should be based upon the merit of your content: the summarized answer to the question he answers is, ‘attract as many back links as you can, but do it organically based upon quality. Don’t do reciprocated or purchased back links based upon an  ulterior motive.’

The subtle hint is, if humans wouldn’t appreciate the link assume Google’s algorithm might not either.

[youtube:http://www.youtube.com/watch?v=wnquaBa6DSk]

And remember, core organic SEO [without gaming] is based upon:

1) focused, well formed & consistent content,

2) a measurable reaction from humans to that content [back links, SERP activity, bookmarks, subscriptions, feed connections to other sites, time on page, etc., etc.] and also

3) well configured / easily spider crawled sites.

Still confused, try This ‘Laypersons Guide To Understanding SEO’ for some more depth