I've said time and time again, based on my own experiences, and what we know about celebrities(Brande Roderick, Leticia Cline, Jenny McCarthy, etc) for whatever reason a lot of hot blondes don't have ticklish feet, even when they're ticklish elsewhere.
However I'm not sure we can add Liz to that list. That brush looks too light to cause a real reaction(my feet are off the charts ticklish, and I don't think that make up brush would have any effect on me). Plus Liz's feet are caked in dirt, mud, so that would lessen the sensitivity.
In addition, I also came across this little nugget of info(not sure how reliable this is);
http://franklypenn.com/2011/08/08/before-they-were-stars/
You have to weed through a lot of crap, so I thought I'd paste the exact paragraph, regarding this topic;
This is why I get so excited at the prospect of any further connection to celebrities in the Six Degrees of Kevin Bacon that is my life. Since I started working here at Penn, I am merely two degrees away from the lovely 30 Rock actress Elizabeth Banks, C’96, and I cannot tell you how excited that makes me. The one degree between us recently revealed to me that “Liz” Banks is “wicked ticklish.” WHAT. How does he know??? New York Magazine has a great feature on her that reveals that she met her husband on their first day of freshman year at Penn. Cute! I mean, shoot. I just forgot the last bit of AP Calculus I had in my head now that I know that fact