Common sense. It does come into play when evaluating what is reasonable and what is not. No reasonable person thinks that Hunter was paid such huge sums of money from foreign entities just because his last name was Biden. How would that benefit those that paid him? Common sense dictates that they didn't just do it out of the goodness of their hearts.
Um, again, people don't pay for nothing. Name dropping won't do it. Simply, "my daddy is VP Joe Biden, give me some money" doesn't work. They expect SOMETHING in return. Most of us know that something isn't just a back rub.