I'm afraid I have to disagree with that. In my experience, there are more people who are more ticklish on their upper bodies than on their feet. Frankly, finding models that are truly foot-ticklish, enough that they react in interesting ways long enough to get a decent amount of material (as opposed to models who only react "part-time" and require techniques that are hard to use and don't always work), is relatively hard. For the upper body, it's not that big of a challenge. Oh, a lot of people will react well to being foot-tickled in an ordinary, everyday context, especially if it's spontaneous and short. But a tickling video shoot is a very different thing. One's reactions to tickling is often heavily influenced by psychological factors. A person who's usually very ticklish in everyday life, say when playfully surprise-tickled by her boyfriend or whatever, may turn out to be a lot less ticklish during a video shoot. This tends to happen more with the feet than with the upper body. Feet are actually somewhat harder to tickle than the upper body, for various reasons. When I ask candidates where they're ticklish (or thinks they are), feet are often mentioned, but not as often as the upper body, and even when both are mentioned, most of the candidates say the upper body is the worst, be it the armpits, belly, waist, etc.
Anyway, in my opinion, the first lee's situation is far from unusual, and many of my models are like that. It doesn't necessarily mean that they're not very foot ticklish. It just means that they're often more so on their upper body. Still, finding good models would be a lot easier if foot tickling were as reliable as upper body tickling. Which is a shame, because I personally prefer foot tickling. Of course, this isn't a problem for people who prefer upper body tickling or who don't really have a preference.