I should have stayed out of this, but in the spirit of education (as in keeping your kids completely ignorant of drugs doesn't help them one bit), here goes:
I know full well that almost everyone that has shown steers at a high level for a very long time in Texas or Oklahoma has done it or seen it done - folks that some of you commonly deal with and sell to or buy from.
I've never seen a steer aired for a show (as in going in the ring with air in them) . I've had calves fitted by some of the biggest names out there. However, for a very long time (decades), and still currently to a probably much lesser extent, steers are aired periodically throughout the year to supposedly cause them fo fill in with a little extra subcutaneous fat to give them a smoother look. Stop and think about it, you can't make one look a lot wider than they naturally are - not without it looking absurd.
I've heard lots of people gripe over the years and accuse people of airing a calf at a show (almost always a county, almost always someone that never spends time with a calf accusing the winner of cheating). I've been able to put my hands on some of those calves (at a county show for example) and have never felt one with air in them. There's a reason officials say you can't prove it - there's nothing to prove.
It's extremely obvious when a steer has air in them.
As some of the "old timers" alluded to, it's nothing new, its been around forever, and the both the so-called "benefits" and sideffects on the animal itself are very minimal. Their skin isn't ripped away from the muscle by it - grab a handful of hair and pull and you can see that a calf's hide isn't attached to the muscle in the way human skin is attached to our other tissues. The multiple subcutaneous shots are what hurts, not the injection of air itself. It doesn't hurt the calves nearly as much as many other "legal" procedures do - such as cosmetic dehorning. You can't do something that really hurts an animal and expect it to still be controllable - certainly not the extent one has to be in order to be shown by a little kid.
Some bulls and baby steers are probably aired for photos. I've heard of that. However, over the 25 years (since mid 80s) I've been involved in showing, I've looked at steers at many, many places and never seen any trader/breeder, big or small, try to sell me or anyone else an "aired" steer. I have had them offer to do it once we bought them, just as part of the process to get them to the end, but never for a show itself. I've had a few have the famous "butt shrink" after getting them home, but it wasn't due to them "deflating". More a loss of hair and fat when put on a normal diet as best I could tell unless they were really "roided up" years ago as babies, which I doubt.
Short story for anyone thinking of doing it: It's not worth messing with. It's not necessary to win. It's not why someone is getting beat. It's an old artifact of how things used to be done in the 70s and 80s and the people that still do it just because that's the way they were taught to do it - by their grandpas in many cases. It doesn't have a substantial benefit on a calf. Although it's not torturing an animal anywhere near to the extent that some of these posts speculate, you can get one hurt from kicking the chute when he gets stuck with a needle in a sensitive spot. You also run the risk of infections from too many subcutaneous injections.
I do not believe that "oiling" is done any more. I've never seen that or heard first hand of anyone else doing it. There's no way it can be done for a terminal show and not get caught.