@hingehead,
Re shopping + apparel -
Thinking, thinking, I might have clicked on a clothing ad once, mebbe a year ago.
And now the light dawns - I used to read The Sartorialist, a clothing photography site, and sometimes I couldn't get in to it, something defective about my cookies, and I clicked on the ad next to the photos. And then the next time I couldn't get in again. And so on - but I block cookies from third parties and advertisers.
I guess that explains a lot.