Agree with the OP. Our competitor did massive link buys from an SEO company (in fact two SEO companies). We submitted a spam complain with exhaustive evidence...and nothing.
Know somebody who attended a conference with one of the tripadvisor guys...he got chatty and admitted the reason why they're all over so many keywords is that they buying their position with links.
So sad that google isn't catching these guys but seems to be punishing the small mom and pops that get pressured into shady seo companies to stay even.
And to add insult to injury google gives tons of duplicate listings to these cheaters because how their clustering algorhythm works (or rather doesn't work).