Service personnel cannot and should not tolerate nauseating and/or potentially harmful working conditions on any vehicle.
Never hesitate to politely but firmly reject the vehicle until the owner cleans it up to your satisfaction.
At one point or another, most—if not all—service writers and/or technicians have encountered extraordinarily filthy and/or smelly vehicles. By filthy, I mean a back seat literally filled with trash and debris; I mean a vehicle with trash or filth several inches deep on the floor or seats. Or a vehicle interior so cluttered with fast-food scraps, leftovers and wrappers that the technician who's trying to tidy it up to a tolerable state finds a dead mouse under the debris.
I'm describing a vehicle on which a luckless tech must work under a dashboard for more than just a few minutes—perhaps doing jobs such as replacing a headlight switch, blower motor, heater core, etc. However, the stench there is simply frightful because a mouse managed to sneak inside an air duct and die there.
Now, if you haven't encountered this situation yet, the source need not be as large and/or overtly smelly as, say, a skunk. No, experience shows that an itty-bitty mouse can smell up a car's interior so badly that you can barely stand to move it into a service bay, let alone keep your head under the dashboard for 30 minutes or more.
Another example is a careless, novice fisherman who catches a big carp, wraps it in old newspaper and leaves it in the trunk of his Mercedes in mid-summer.
I'm talking about a customer who parks a car in a carport for several weeks with some windows partially down in order to allow fresh air to circulate through the interior. Unfortunately, that allows bees to wander inside the car and build a nest. Or, think of a set of circumstances where rats somehow were attracted to a vehicle and then took refuge inside it. (Perhaps you haven't seen damage until you've seen what rats can do chewing on wiring harnesses!)
No doubt there's bad luck in this world and some of us have witnessed that when our service writer or tech—not the car owner—is the hapless one who finally disturbs the insects or vermin during a road test or when moving the car into a bay. And in case you haven't noticed, it's not easy keeping control of a moving vehicle when you're being bitten or stung.
I've seen some of these almost science-fiction scenarios firsthand. What's more, I've heard about them from technicians I meet during my cross-country travels. But the aspect of this issue that takes it from mere science fiction into the realm of absurdity is the boss who thinks the problem is his responsibility. Frankly, some motorists also think that raking out trash, fumigating and exterminating vermin are your responsibility. Not so, I say.
The last time I checked, the condition of a vehicle always, by default, begins and ends with the vehicle owner or caretaker. Issues such as extreme trash, extremely sickening odors, rodents, etc. are wholly the vehicle owner's responsibility—not yours because you didn't cause it.
No matter how freakish or bizarre the problem, it's not your problem—unless you left the windows rolled down, for instance. What's more, no motorist should be allowed to put your crew at risk of sickness or injury, especially when either the customer's bad luck or gross negligence create the problem in the first place.
Furthermore, the road to hell is usually paved with the best of intentions. You may think it's a kind and wholesome gesture to try to fumigate or exterminate the car yourself. However, these tasks usually aren't the forte of automotive repair people. You might fail miserably—or else fail to do a thorough job.
If so, then you may expose yourself to liability for it. (If nothing else, you may have failed in the customer's eyes to do what you promised to do.)
I recommend playing it as safe as practically possible. If you discover an unusual condition, move the vehicle out of the way as quickly and safely as practically possible. Then politely but firmly insist that the car owner schedule an appointment with his or her favorite fumigator or exterminator. Then allow that specialist to take responsibility for getting the vehicle into a safe, non-threatening condition for your technicians to service it.