Well, there is no accounting for how juries interpret the law, but in general they are asked to determine an issue of negligence, without really knowing what the term means to the lawyers. That difficult decision is made more so by the fact that in most cases there can be more than one person or entity who is negligent, so that the owner of the beagle might be found 1% negligent by not having a required or expected warning sign "beware of Beagle" for example or of failing to train his dog never to bite regardless of provocation, and the dog tormentor 99% liable. In the best case this might reduce the total damage award based on a fractional apportionment of the total damage (assessed as a separate issue from the question of who is at fault) to nearly nothing. In many cases, joint and several liability and similar doctrines require that even if only a tiny fraction of liability falls on one defendant, he is responsible for paying the entire amount of damages. In some jurisdictions a dog bite is by statute the legal responsibility of the owner, regardless of what precautions they may take to prevent the bite from occurring, so showing that the defendant owned the dog proves liability. If you want common sense justice, stay out of court.
As to the McDonald's coffee spill, the facts are frequently mis-stated as they are here. The victim was not driving, the car was not in motion, but the coffee was dangerously hot, and McDonald's had been presented with numerous cases of similar injury, and had due warning that the company's requirement that coffee be served at a known dangerous temperature put customers at risk. It was only after the success of the suit that a safer temperature was adopted.
http://www.lectlaw.com/files/cur78.htm Often these unjust decision horror stories misstate the facts and the law as well.