Left 4 Dead

You can easily differentiate between Smokers and other infected as Smokers kill the survivors by gripping them with their stupidly long tongues. When you notice a survivor is being gripped by one, simply follow the tongue back until you reach the Smoker where a few shots will kill them as they are not very strong.

Speed is the essence with this one!

This achievement glitched for me... in a good way.

I cleared my cache for other reasons and the very next time I started up L4D, this achievement unlocked along with 20 Car Pileup (both popped on main menu, before pressing start).
I had previously played L4D2 and still had a guest signed in, only have the Crash Course DLC.
I previously only had about 5 or 6 smoker kills and absolutely nothing towards the 20 cars.

Let me know if it does/doesn't work and if you have a guest or not, and what DLC you have :)


EDIT: after I cleared the cache it said I didn't have the Crash Course or Survival Pack DLCs. I thought I'd try clearing the cache again to see if any more achievements popped (they didn't) and the next time I started L4D it said I had the DLC again. So instead of re-downloading any DLC, just clear the cache again.
And no, this did not affect my progress towards other achievements (such as Zombie Genocidest).

This guide is a bit late to say the least but I haven't been able to find a correct solution anywhere else on the internet, so I figure I might as well post it to save people some confusion.

The description of this achievement is incorrect; you DO NOT have to kill the smoker, you have to shoot its tongue. I tried multiple different levels and solutions in order to kill them and the bar never went up past 8/10, but the first two tongues I shot - without killing the smoker - got me the rest of the way to the achievement.

Getting this achievement in single player is relatively easy; however, it is a bit tedious and luck-based. So what I did was I went into a split-screen Versus private match on the campaign "The Sacrifice" and picked chapter 3 "Port Finale". This is because the special infected that will ALWAYS spawn first is a smoker.

With my second controller set to be the infected, I killed all but one of my teammates and left the saferoom; this left the last remaining AI out in the open for the smoker and an easy tongue shot. Simply rinse and repeat for however many smoker tongue shots you have left.