Can you get good ranking in the search engine with links from non relavant websites? It seems that links that are from websites that are similar to mine are more expesive or harder to get. On another site of mine i noticed slipping in search engine ranking the when I got a few non relavant PR 7 links?
You can get good rankings from non relevant links but in general relevant links are believed to be better. I don't think your ranking will have gone down bacause you got certain links, its probably coincidence.
If you are going after non-competitive keyword non-relevant links with good anchor text should work ok.