No, the dog definitely realizes, trust me. And you may use the powder just for grabbing the hair, but not every single person is doing that. Some people dump powder in the canals for drying. Some people just use it for the hair, but don't clean the ear as thoroughly as they think they are. You just said you just use a cotton ball and wipe the ear, so if that really is all you do, it's definitely not thorough. A thorough ear cleaning involved CTAs and pouring a bit of cleaner into the canal itself. Now you might better understand why I cringe when people talk about powder. The only places I've ever known to do a real thorough ear cleaning is a vet clinic. I'm not saying to run out and start using CTAs at a groomer's, you can potentially cause harm with them if you're not careful/trained...but you can imagine that any water/shampoo that may have gotten into the canal will still be there, as well as any powder that found it's way into the canal. I wipe the external ear of my dog/cats when I'm doing my weekly stuff, but anytime I bathe I make sure to at least get a little bit of a drying cleaner in their canals and let them shake out any excess. You don't have to irrigate a healthy ear necessarily, but it helps to dry out any residual moisture.
I've never heard of these tablets but a quick google search is telling me that these are designed for a dog's coat, not it's ears

Although the website I'm looking at (as well as some of the Amazon products) also claim that the CO2 tablets cause CO2 to cross the skin, enter the bloodstream, and increase blood flow. I swear people will believe anything you tell them...it just sounds like a gimmicky product to me. If someone is crushing/breaking a tablet and adding water, that's obviously not okay especially if it fizzes.