Costco (NASDAQ: COST) has been killing it.The warehouse club has shown that doubts about its long-term viability due to the so-called "retail apocalypse" are unfounded. The company saw net sales rise in the third quarter by more than 12%, consistent with its recent performance. In addition, the retailer saw same-store sales jump by 9.7% (7.7% when you exclude gas) in Q3 in its U.S.