I never used them to begin with, but lately I've been finding you have to stand in the smoke to receive any benefit, when I had thought since the inception of CoH it was any projectile passing through it. So I just don't know anymore.
I suppose it is possible that the it's the low scatter on the weapons hitting you? but smoke is supposed to give a 0.25% accuracy modifier
I think you have to stand in the smoke, but in doesn't help anyway, I tried it again yesterday and every shot still got a direct hit. This was from a P4, a Panther and a Puma. I hade 2 tanks with smoke on and every shot still got direct hit.
EIRRMod told me that it is a 0.50% accuracy modifier but I don't think that can be true.