helleborine - 9:17 pm on Sep 8, 2012 (gmt 0)
I'm pretty sure that Ehow's Spark takes a screenshot of your browser display - if so, the image background substitution trick won't work.
Pinterest does identify itself in User_Agent when a pin is made, so it can be beat in htacess.
Loveit.com calls up an image from one of its servers, so it's identifiable, so it can also be beat in htaccess.
Spark? I have no clue how to beat that one. I am stumped.
I do think search engines should ponder giving these websites a taste of the SERP gutters.