First of all, if someone wants to smoke cigarettes, that's their choice. I don't, and I really don't care for it, but I don't aim to run anyone's life for them. I have enough of a time keeping myself out of trouble. I don't mind working on a computer that has been smoked around...warranties are something else.
I don't know how much harm the compounds left behind in a computer would really cause to someone working on it. It
seems feasible that any person could have a problem, even if it was no more serious than just being "grossed out". I know I've worked on more computers than I can count that were owned by smokers. The worst one came from a guy whose apartment walls should have been bright white but were actually dull yellow. I could not see any identifying marks on any component part in the system. I also couldn't make out any of the fan paddles.
No matter how much you might like to smoke, you might stop when you looked inside anything in your home that has a fan going inside it.
I really didn't want to touch it. I had no idea what to do about it. So I threw it in the dishwasher after making some preparations. (Bet that got your attention, didn't it.) Chucked it on there with a ton of detergent, the hottest possible water temperature setting and the longest wash cycle I could pick. It was not completely successful as the system smelled of cigarettes afterwards, but it was a 9000% improvement from what it had been. Stuff was the right color again.
More recently, I inherited a Dell Dimension V350 PC that had a lesser form of the same disease, and I decided to show the world one way to fix the problem:
http://www.youtube.com/watch?v=ahhSDEgkqQ8 . If that sort of thing interests you, please go and watch.
At the same time I fixed a fax machine that faxed entirely in black. Yep, you guessed it. A fine line of cigarette residue covered the optics, making it impossible to read a document.