Anarax
Master Black Belt
With regard to finger locks and BJJ, I'll just repeat something I mention sometimes when people say "style X (boxing/wrestling/Judo/whatever) is a sport, they don't know how to do (insert dirty tactic here), it's against the rules."
If the technique in question is against the rules, it doesn't necessarily mean a competitor in that sport doesn't know how to use it. It may just mean they know how to do it in such a way that the ref can't see it.
Just saying...
I understand what you mean by style x and dirty tactics, I'll come back to that. I was thinking of one FMA concept that could be taught to BJJ practitioners. Defanging is a major concept that I think many martial arts could incorporate. Regarding seminars I think having a more concept based approach offers the attendees a better opportunity to expand their knowledge opposed to only showing techniques.
Dirty tactics aren't really a "you don't know this technique", which I agree people incorrectly make it out to be that. But I think it has more to do with changing the way people think. Something as simple as eye gouging or finger breaking can be done by most people, but instilling the mindset of how you would deal with a fight differently opposed to rolling in practice is a crucial thing to ingrain. Meaning in a training environment we obviously can't practice such techniques to completion. However; they are techniques that should be used in a real altercation(eye gouging only in extreme cases) if the opportunity presents itself and the concept should at least be touched on and incorporated into training safely.
My Goju teacher had us do ground grappling at the end of sparring class. Though ground fighting isn't something I would consider a dirty tactic, it's still something as Karateka we needed to start thinking about and incorporating into training.
The OP even used the example of BJJ practitioners that have a more self defense mindset, which makes the small joint(either finger or unfamiliar wrist locks) that much more appropriate.