Starbucks' sales results were pretty dismal in the second quarter of 2024. This is what investors need to be watching right now.There's no way around it, Starbucks (SBUX -3.64%) had a rough second quarter. The large coffee chain simply isn't resonating as well with customers right now. While there are a number of reasons why this could be happening, investors should be paying extra close attention to sales and, more to the point, same-store sales, right now. Here's why.What went wrong at StarbucksStarbucks ...