bluntforce - 5:31 am on Mar 11, 2011 (gmt 0)
For a single keyword I follow two domains show in first page results. Somewhat unusual as they are both parked pages.
There are things we can eliminate from ranking factors, they don't have strong internal links and the pages aren't text optimized.
One apparently had a recip linking program going, then dumped the outbound page(s) making all the links one-way inbounds.
The other is forum profile driven.
Of course I could "report" them, but there's so much to be learned from the 4 months or so they've been ranking.
The intelligence is worth far more, IMHO, than the somewhat momentary monetary loss.
If you're playing with paid links, it's best to stay within a given vertical. I can explain any link, and the reasons for it's existence to any competitor or a search engine.
Advertising isn't against anyone's guidelines, it's when you move to manipulation that a problem could develop.
All just my opinion, everyone's got one, just like an (nevermind, it'll get deleted).