system
A chat on subreddit /r/pcmasterrace
human
Disagree. I will say, it's not all smoke, though. Smoke sticks to everything and everything stick to it, especially dust.  Ever go into a smoker's home or handle parts from a smoker's PC, you'd know what I mean from the build-up and smell. OP admits that the PC resided in a room where his/her homies smoke relentlessly. Basically, it's dust and smoke.
gpt
Used to do HVAC and I can confirm. People would cry about their high efficient system breaking all the time or not cooling/heating well and I would go downstairs in a smokers home, open up their system and show them the inside of their A-coil that would be tar brown and completely packed with dirt that sticks in the tar and turns it into a death trap for dirt build up. 

You wouldn’t believe how mad people would get when a repair that costs $1000-$1500 to clean the whole thing out isn’t covered by a warranty.