This is something I'll always say. If creators were honest about the ticklishness of the models, or were upfront about their studio faking tickle videos, this wouldn't be an issue.
The problem with this is the default assumption that producers
must fake at least some of their content. For those of us that don't it's a no-win situation - whatever we produce, someone will inevitably assume that the laughter is fake or forced, based on their own experience, beliefs etc. Speaking purely for myself, I don't fake anything
unless it is a specific custom request for the model to react a certain way, or give scripted reactions. That's something I dislike anyway and generally don't release such clips (I don't really do clips with stories etc). Likewise, I don't release clips if I don't think they're up to scratch or the model is having an off-day or whatever. I don't think I'm alone in saying I have nothing to admit to in this respect, but some viewers will never be persuaded.
If, however, the tickle clips you're buying involve a fantasy scenario, roleplay, story line etc then you should absolutely expect that not everything will be completely real. This is the point about Hollywood movies - if people have to act in the clip then they are going to be acting regardless of whether they are actually ticklish. They're required to say and do the things that the script requires. I find it odd that people want to see these scenarios but are then upset to find the model hamming it up. The simple solution is to not buy story-themed clips, but please don't assume that everything is fake just because a model had to act a certain way once.
I've seen such videos. You're talking about story. They ain't faking the sex. The camera placement informs us that we're not watching an episode of The Red Shoe Diaries.
I've shot with 2 real stepsiblings (I had to get images of their I.D.'s as a legal requirement.) They were both crazy ticklish. On some shoots (not with me) they even got the mom/stepmom involved. Stryker has done at least 2 shoots with a mom/daughter combo. Tickle Intensive has used cousins (one has since retired😉 if they were faking, the viewer had no hint.
Ironically, mainstream porn contains vastly more fakery at every level than the average tickle clip. Porn models generally love sex but it doesn't mean that they love every scene or even enjoy them. I know plenty of situations where performers don't get along, actively dislike each other or the director/crew are massive assholes. Fake orgasms, fake squirting, even fake cum...they all happen, along with hours spent just trying to get the one money shot. And absolutely none of the step-daddy/daughter/mommy or neighbour scenarios are real of course. As you point out, many tickle producers do use actual siblings or relatives in their videos - I've shot with models' cousins, sisters, twins, mothers and best friends - and they're all legitimate relationships. That would never happen within mainstream porn where it is all pure fantasy.