I'd like to point out personal preference is more likely to blame than a conscious decision to use half-assed models. I think TMF thinks a lot of the population is thrashing, red-face, eyes bugging out of head ticklish and demands to see that in their tickleporn, and anything less is a copout. But someone is spending the money to make all these "fakers" profitable to keep hiring, no?
In my limited experience with video producing, I've had girls I thought were going to be widely popular not get more than a handful of vague compliments. Girls I thought really didn't react worth a shit, and indeed may have been faking some of their reaction, are far and away my most popular. What realistically can be done? Judge it on your own merits? If I only did that I'd have a webpage of people that evidently appealed to me and me alone. Everyone's sick of conga line of fakers and pornstars dominating Clips4Sale? I'm right there with ya!... except, wow... according to that best seller list those fakers and pornstars sure move those clips.
Obviously everyone wants to find someone you can barely touch who will go apeshit, laugh until she's horse, shake and struggle until the bedposts nearly break and somehow be able to last a half hour. There's a lot less of them out there than you'd think. But why settle for porn girls and fakers? Well, who the hell keeps buying those videos?