I've got two thoughts here:
1. Since Camoes are unlocked by getting headshots, everyone is aiming a little higher than they used to in order to maximize the odds of getting them.
2. Most of the guns have a vertical recoil. So if you aim properly the second bullet will often land you a headshot and/or if you flinch upwards then the first bullet has a chance of being a headshot.
I get quite a few headshots in most matches or at least what I consider quite a few anyway. Often between 2 and 4 per game. Considering that I typically kill around 25+/- per game that's anywhere from roughly 10 to 16% headshots. That's without carefully lining up my shots but rather just generally positioning my gun to take advantage of it's recoil pattern.
The only way to avoid slop shots would be to make your opponent call out where they plan to shoot like in a game of pool. You could check the results and see if the game is reading accurate. Then you would know just how good your opponent actually is, and how unaccurate the shot tracking is in the game.
This would be and interesting way to play the game.