I agree with Planet13. A lot of the times you see a lot of junk links being indexed or in seomoz or another link checking tool, but none of that really confirms that link juice is being passed. With really spammy ones I wouldn't worry about it.
I personally wouldn't report another site. It's frustrating sometimes that we have to always bend to Google's will. I'm not saying I do black hat, but everyone here knows they have gotten a link or two in a way that Google wouldn't approve. I sort of look at it from a karma perspective. Although I'd love to outrank some competitors, I could just as easily get reported for even a minor case and have to deal with a manual review.