What difficulty level are you on? I normally just have it at default and it doesn't affect me even on day 1. The zombies aren't high level, so it's not hard to kill them even with my Q1 stone spear. It's not really a problem unless I'm not paying attention. Like I said, I don't worry about smell at all, at any point in the game, and it has never been an issue. I kill more zombies, but it's not really a challenge. I can see it being a challenge for new players, and perhaps if you're on the higher difficulties.