A gecko (or any animal) may not have a concept of what's normal but they don't really have a concept of self, anyway. A gecko suffering from enigma syndrome can't tell itself that the death rolls or spinning will stop eventually. That a treatment is the works or up for review by the FDA. And...
If there's a genetic issue that can severely impact on the quality of life of something then it should be stopped. The leo being beautiful doesn't make up the fact that it's doing death rolls and can't properly walk.
It makes me think of people who know they may carry the gene for Huntington's...
It's good to have a chance to interact with an animal seconds before purchasing but the chances that it's well cared for are slim. I'm not going to pretend I know a great deal about any given reptile but most of the employees I've encountered didn't even know enough to BS me. Minus the good...