Sgt_Kickaxe - 4:25 am on Dec 28, 2012 (gmt 0)
This reminds me of when BMW didn't show up in serps because they employed an SEO who was up to naughty things. It's very possible that the site has some sort of penalty.
CanuckSEO - technical issues can indeed hurt your rankings but fixing those issues generally sets a site back on course fairly quickly even if some pages may take years to get above water again.
If they have some of the best incoming links around but also 100x the number of shoddy links when compared to a similar site the good links may not be strong enough to hold? Only Google knows.