Corexit smells a lot like ammonia. Think of the smell you get when you clean your windows and countertops with Windex. It is a smell that masks other odors and one which we associate with being "clean". Kind of like the false sense of security and cleanliness many get when they spray toxic household deodorizers like Oust.
People in the mobile home industry have long used ammonia to mask the odor of all the formaldehyde from the glues and chemicals in the plywoods, pressed woods, carpets, and other materials used to save cost and weight.
Similarly, you could take a smelly days old fish and soak it in Windex and mask the smell of rotten fish.
If something does not smell rotten it is safe? WTF kind of illogic is that? What about actual water, air and fish toxicity samples from trustworthy sources which haven't been bought off by BP or aren't beholden to the state economies and peoples who depend on fishing and tourism?
Quite simply, the gulf is not safe, the fish are not safe, and they are not likely to be safe again in our lifetime. Ultimately, the gulf will reach some kind of equilibrium, but it will not be the same equilibrium it once enjoyed. Not at all. Here is one example: sea water contains aresenic. Normally, the large majority of the arsenic reaches the ocean floor and mixes with silt which keeps it from accumulating in the water and the fish and other marine life. Not so when there are oceans of oil in the water and on the seafloor. Arsenic levels are likely to rise in both the water and marine life. Just one more BP bonus for us all . . .
No matter what they spray on the gulf, it won't cover up their foul deeds or make it healthy any more than the copius amounts of cheap perfumes once used by unclean and often infected hookers before clean water and soap became plentiful made them clean and healthy.