I think it goes deeper than just having a backup plan if the "dirty trick" doesn't work. Many of the dirty tricks are lower percentage than some of the other potential responses. So, potentially, a better plan is to learn and use those other responses as a primary plan and save the "dirty tricks" for the backup plan, or maybe even roll the two together.
I remember in the early "Sport Fighter vs. TMA" arguments, I used to see "I'll just eye gouge or nut grab" him a lot as a response to stopping a grappler. The assumption was that a grappler was unaware that EMFG's existed and couldn't use them at all. But the reality is that a person who is conversant with grappling usually ends up in a superior position to not only prevent an EMFG but is actually in a better position to perform one. Basic grappling skills can actually enhance your ability perform "dirty tricks."
That's the point of not
relying on "dirty tricks." It's not that they don't deserve a place in your bag-o-tricks, it's that we need to know how to actually use them and, as it turns out, it's not what a lot of us (myself included) believed they were prior to the "Gracie Revolution."
I haven't given up EMFG's or GroinGrabs from my martial list, I just have better ways to more effectively apply them. They're higher percentage techniques now.
Peace favor your sword,
Kirk