My girlfriend is a lovely tall blonde with very pretty feet. Her big toes have that slightly upward curve to the toenails that make them so cute. When we first started dating, she said her feet weren't ticklish. I couldn't get a reaction out of her. I tried soft and hard with my fingers, q-tips between her toes, and sucking her toes (which turned her on), but none of it tickled.
Then one day I decided to dig in really hard on her arches for several seconds and she jerked back and said "don't, that's cruel". I said, "Did I finally figure out how to tickle your feet". And she said, "yeah, you finally broke me down". I also used my teeth on her arches and toes, and she reacted some to that as well. I guess she only responds to a "deep tissue" tickle technique, but then I wonder if it hurts more than it tickles (kinda like digging in to people's ribs), and I don't want to hurt her.
Unfortunately, some days this technique still doesn't tickle her. Its kinda like she has to be in the mood. Also, one of her feet hardly reacts at all. It kills me that I have to work so hard to tickle her feet. I really miss those light tickles that have worked so well on other girls I dated. When I run my finger across her sole and get no reaction its just torture for me. I am trying to adjust because she is such a good girl, but I don't know if it will work.
I have never tried to tickle girls with bad feet, so I don't know if there's a connection between nice feet being not ticklish verses bad feet being ticklish. I can say that of all the girls I have tried to tickle, all had very cute feet, but only about a third of them were really ticklish. Most were slightly ticklish or not at all. Unfortunately, many of those girls said they had ticklish feet, but really didn't. I am in my 30's, and I can count on one hand the girls I knew with very pretty feet who were unbearably ticklish. When you add that to all the other things necessary for a successful relationship, its like looking for a needle in a haystack. I don't know if a single lifetime is long enough to find it. Don't mean to sound depressing, just my observation.