I used to do computer support at the business where my sister was office manager.
( I got the work because I was cheap.)
So in the upstairs office where the accounting department was located, there were five women who were all smokers. The computers absolutely reeked of smoke and the insides were brown. I only ever brought one home to repair, after that I did all repairs onsite.
I even found a dead mouse that crawled into a 5 1/4" floppy drive once. Never smelled it, as it was probably overwhelmed by the smell of smoke. I think he died of cancer.