@Srksii Well, the only way for people to see into the smoke from the outside is to have a digital threat on a pistol, (since sniper ones are now disabled for some reason), while those inside of the smoke will see a white outline of others who are also inside of the smoke.
As far as I'm aware of as well, aim assist is disabled when the target is in smoke, even with the outline.
The thing about the smoke however, is that most players would sit in the center of it as the edges makes you more visible. With that being said, shooting blindly into the center is one way to hit someone sitting in the middle of it.
The only other thing I could think of is that players have the smoke disabled, (which shouldn't be possible as I've heard its been patched for a long while now), so you're most likely are just running into cheaters.