1. If something at a yard sale is far more valuable than the posted price, do I have to let the seller know?
A: A piece of furniture you've been searching for is marked $25. You know that similar pieces in worse condition have sold for more than 10 times as much. You're under no obligation to correct the seller on her underpricing. One of the beauties of yard sales is such finds. Savor yours.
2 Is it unfair to move into better (open) seats at a sporting event or a concert?
There's no harm in seeing if you can move into a better viewing position. But before you do, make sure there's no posted policy against it. And if an usher asks to see your tickets, be prepared to move back to your original seats without argument.