@PsiCop: Enough to make me sick. I react badly to nicotine, and the tar/nicotine film that heavy smoking deposits on surfaces will make my skin turn red and, in bad cases, cause nausea.

Yes, the hazard to the tech could be avoided with a set of nitrile gloves and a respirator. The hazard to the computer, on the other hand, isn't so easy. Plating every surface inside a computer with goo (which may be conductive) and the dust that sticks to the goo (which causes overheating) is not a good thing. I'd certainly list that under "abuse and neglect". The big problem, from Apple's point of view is that cleaning that computer, before they can even start diagnosing and repairing it, is a multi-hour job. You need to tear everything down (that stuff gets in EVERYWHERE) and go at it with swabs and solvents. So a job ... say, a keyboard swap ... that might take 15 minutes in normal circumstances suddenly becomes a four hour job. Apple prices their warranties on the assumption that they will do, on average, X amount of work per buyer. Abused computers -- whether the contaminant is smoke residue or Pepsi residue -- throw that estimate way off. People who take proper care of their computers would resent having to pay for those who dump Pepsi all over them ... or coat them in smoke goo.

A few other odds and ends:

Hard drive platters are usually sealed, yes, but their electronics aren't. That goo can short, corrode, or otherwise mess up those circuits and cause failure. (so can Pepsi and other things that should never be introduced into computers)

OSHA has standards for all sorts of things.

Peroxide, for instance: The diluted form you buy in the drugstore can be used as an antiseptic. The concentrated form you buy from chemical supply companies can be used as rocket fuel. As a monopropellant. Peroxide torpedo propellant is believed to be the cause of the explosion that sank the Soviet nuclear submarine Kursk. It's also one hell of an oxidizer.

Isopropyl alcohol is another good example. It's toxic if you drink it. It's highly flammable. It can react with other chemicals. The fumes are a nasty irritant. I'd have to check with a CIH, but I'm fairly sure that breathing them for more than a brief period goes beyond 'irritant'. Just because you can buy some in little bottles at Wal-Mart doesn't mean it isn't a hazard when you have 55-gallon drums of the pure version stacked up in your factory.

Chlorine. Read the warnings on a box of chlorine pool shock some time. Don't touch it, breathe it, be in the same ecosystem with it, etc. Chlorine gas is lethal. Chlorine is another strong oxidizer, and reacts with just about everything. Damn straight OSHA lists it as a hazardous substance, because it most emphatically is.

In a lot of cases, it's all about concentration and explosure. Sound isn't a bad thing, right? We hear stuff all the time. But when you're listening to a jackhammer you're using, and you're listening to it for 8 hours a day, you can go deaf. So there are exposure limits for sound, based on decibel level and exposure time, and standards for protective equipment (read: earplugs) to mitigate the hazard.

Or oxygen. You need it to live, but too much of it will kill you. Liquid oxygen can be fun to play with if you want to not just light your BBQ grill but remove it from this plane of existence (google for remarkable pics).

There's also the question of whether what Ruth looked up was in fact a list of available MSDS sheets (yes, I know that's redundant, like PIN number). There's a MSDS for basically everything. Water, for example. Why would you need an MSDS for water? Because it lists things it shouldn't be stored with or exposed to. Alkali metals, for instance. Water + Sodium is all sorts of fun, if you like that kind of thing.

As for nicotine ... the lethal dose in humans is approximately 0.5-1.0 mg/kg, and it is readily absorbed through the skin. So going with the high end of that, a 150-pound tech could be killed by 68 mg of the stuff. Possibly as little as half of that. For those of you uncomfortable with the metric system, there are 28,000 milligrams to an ounce; you do the math. Is someone going to absorb enough nicotine from working on a goo-coated computer to kill them? Doubtful. Absorbing enough to make them sick, on the other hand, is very possible. Google "green tobacco sickness".

So yeah, there could be an impressive layer of crud (I once had to wait for someone to, among other things, scrape the crud off apartment windows with a razor blade before I could move in). It could make the tech sick. Probably more important to Apple, it could make a repair time go way over its time budget. The fact that it's a foreign substance and a contaminant inside the computer (just like a can of Pepsi) almost certainly brings it under the "abuse and neglect" part of the service plan.

So, in short, Apple doesn't have to fix it, just like they wouldn't fix a computer that got flooded with soda.

Apple, you sometimes drive me crazy

That's better than what I keep by my toilet!