Ask HN: Understanding the Mystery of Adwords QS

I'm not asking what goes into Adwords QS or why mine is always low. I just about have never had any success with any thing I've tried to advertise on Adwords.

But, I'm posting this question because of one main thing. I've come across a large amount of ads that rank very high (position 1-3 consistently; which means they much have a good QS), that feature landing pages with little to no text at all.

How could adwords possibly assign them a high QS for a page that is 95% images?

Examples: https://www.demandbase.com/signup_freetrial_a.html http://www.centraldesktop.com/l?sr=googs&sy=col_onl_np https://www1.gotomeeting.com/t/gg/online_collaboration-Broad/NAPPC/g2msem3 http://campaign.mindtouch.com/C/Download_MindTouch_Deki/4?copy=4

..you get the point