Implied warranty laws apply everywhere in the USA. It’s just that it’s a matter of 50 individual state laws, not a federal law.
Not around here! But I remember my Dad thinking that is was different here in Aus than it was in the USA.
Around here, the starting presumption is that if you put up a warning, it demonstrates that you were aware of the hazard, and should have done something about it. We don’t (I think) have penalty awards in civil cases, but it would surely make your case harder to win, and might, in some cases, also lead to criminal or work-safety penalties.
We also don’t have warning labels on dump trucks. They are required to have mud flaps and some other protection to stop them flinging gravel at you, leaking from the load is illegal, and around where I live it’s all sealed roads: you’re not materially more at risk from a dump truck than you are from any other car.
The “Keep Back 500 Feet” signs are especially appalling to me. The truck driver must ensure that his load is secure. He cannot mitigate his negligence by telling me that I have to take special care to make sure he did his due diligence. I can follow him as closely as the law permits and/or as closely as it would be reasonable to follow any other vehicle.
Under the trucking company’s theory, I could mitigate my liability by posting a sign saying, “Driver is intoxicated, please stay away!” and somehow that would make it your fault if you drove near me. It’s absurd.
I agree with the OP that knowingly false statements of this type should be actionable.
Well, I’m not so sure they should be actionable. I was mostly asking whether they are now.
It seems to me that it would be very hard to write a law in this area that was either over-restrictive of speech or unenforceable. You don’t want to criminalize the act of expressing a mistaken opinion about the law. On the other hand, it could be hard to prove that someone did so with (a) the knowledge that the statement was false, and (b) with intent to deceive.
I remember discussing liability with a ski hill operator and a lawyer who was a member there; the operator mentioned that the blanket “assumes no liability” disclaimers still did not stop them from, for example, having to pay for cleaning when melting snow mixed with oil from the lift wheels dripped on patrons’ ski suits. The lawyer added that any case would be judged on its merits and the disclaimer was unenforceable. It simply was a blanket warning that “hey, there are dangers” so the hill has done due diligence. If a patron was hit by lightning, the hill would not be liable; if faulty maintenance meant a lift wheel falls on a skier, the hill is fully liable.
The same would apply with trucks - the sign warns you, don’t follow too close. If even a few people think they can’t get their windshield paid for by the trucker, the sticker has paid for itself. But in the end, it’s the law that prevails.
So to the OP’s question - I doubt that a generic sticker will be considered illegal “not responsible for broken windows” or “no refunds”; but if a merchant say, makes a specific claim that is contrary to consumer law to a certain customer directly during a transaction he could be held liable. Generally, consumer law overrides any specific limits put on the transaction by the merchant. But normally, enforcing that law probably would only extend to full refund. However, a trucker driving down the highway is not making a specific consumer transaction, so probably cannot be held to the same rules as a retail business (IANAL). They can say or post whatever they want. (A broken windshield is a tort not a purchase transaction?)
A company and driver that loads a dump truck so high that a hefty boulder could fall out the back is engaging in criminal negligence - not a consumer law violation. The criteria is whether an occurrence is reasonably (the lawyer’s favourite word) foreseeable. If so, it is incumbent on the operator to avoid it.
Ski slopes are a bit different because almost every state has passed statutes limiting their liability in some areas. In my state they are immune from suit for any “danger inherent in skiing” and they are specifically exempt from lawsuits based upon snow and hill conditions and whether they have groomed the trails properly.
But the things you mentioned are not such risks and dangerous and lawsuits would be permitted to proceed. One of the early cases after the statute was passed, a skier was over served in the lodge bar and then proceeded to ski and break his leg. The Court held that the slope was responsible under the dram shop law and that drunken skiing is not “inherent.” 
This happens so often in Arizona that my insurer has no-deductible windshield replacement coverage without your asking for it. In twenty years I put in four claims; didn’t bump the rates, either.
But my point goes to the core of the OP’s question: (IANAL)
Attorneys can claim anything they want if their client asks them to, absent directly incorrect claims that amount to extortion or fraud. There are plenty of remarkably frivolous lawsuits. The only prohibition I could see would be making factually incorrect claims about a case or the law in court.
The OP also confuses consumer law - about retail transactions - with general law. A truck driving down the road is not selling you anything, so they are not misrepresenting terms or conditions of a good or service for sale to you, you are not a customer.
Last year Apple sued an iPhone repair shop in Norway because they were using aftermarket parts that infringed their trademark. Apple lost. https://motherboard.vice.com/en_us/article/a3yadk/apple-sued-an-independent-iphone-repair-shop-owner-and-lost
I’m confused by Apple’s argument. It seems like an internal component (which contained the Apple logo) was repaired by someone in China and Apple claims that infringes on their trademark? How so?
That seems to me to be the equivalent of having a Chrysler hood ornament on my car, then I replace the hood and replace the hood ornament and then have Chrysler complain that I am passing off my aftermarket hood as a genuine Chrysler hood.
I agree with the judge and it seems pretty clear that yes, Apple can be an exclusive manufacturer and can decide only to sell OEM parts to authorized repair shops. But if I can get my hands on repair parts through other channels, and so long as I don’t claim that I am an authorized Apple dealer, what grounds does it have to stop me?
He’s confused about that? I’m surprised to read that, primarily because I am the OP and I don’t recall mentioning anything about being a customer in my original post. I did go out of my way to mention both civil and criminal law in my OP, but I don’t believe I’ve confused consumer law with any other kind. What leads you to believe that I have?