[citation][nom]tapnick[/nom]I was a geek squad agent for about 3 years and i can say that smoking constantly around a pc will have negative effects on it. Not sure about the whole bio hazard issue but it is pretty disgusting to crack open a case that somebody has been chain smoking next to.[/citation]
Unless it's an extreme circumstance, by the time smoke has had an opportunity to "ruin" a computer, it should be the end of an upgrade cycle anyway.
Yes, smoke can damage a computer and can potentially ruin it faster than in a non-smoking environment. However, with regular care and cleaning, it is not going to be much worse for wear by the end of a computer's average lifecycle.
My parents last computer, I had built for them 8 or so years ago (AMD AthlonXP 1800+). They are very heavy smokers, and the computer didn't give them a single problem, nor did any of the parts (besides the fans) ever need to be replaced. It was not cleaned out on a regular basis either, unless I was able to get some time in to do some general maintenance.
Yeah, the parts seemed to sometimes be a bit extra gunky, but I'd also serviced PCs which were just as gunky and not in a house with smokers. Moisture in the air can easily make dust "sticky" and "gooey", making it very hard to remove it from electronics (and living in Michigan, let me tell you our nasty humidity in the summer easily makes that happen). Canned air can only get you so far, until you have to take a cue-tip or another non-abrasive tool to loosen the gunk up, then either use dust-off or an electronics vacuum.
Yeah, smokers have potential to ruin their computers faster, but then again, so do people who never clean the damn things out. I've run into just as many non-smokers who take terrible care of their computers, that once you open it, you'd swear the PC was in the house with a chain-smoker, only that it doesn't have that smell. They keep their computers in poorly ventilated environments, running the computer in a non-air conditioned room with the temperature outside in the 90s and 100% humidity. That is every bit as bad as a person who smokes around their computer, and actually has far greater potential to cause harm to the computer.
The only part which actually bothers me is the smell, but then again, if you clean it out at least once a month, that smell has a lot less chance to build up. However, it will probably still be a bit noticeable.