The cruising giant reports quarterly results this week. It didn't go very well last time.The past few weeks have been a bon voyage for investors in cruise line stocks. Carnival Corp. (CCL 0.56%) -- the country's largest player by revenue -- has seen its shares coast 10% higher over the past month. This would be cause for a party on the pool deck, but comparison is the thief of joy sometimes.Rival Royal Caribbean -- the country's largest player by market cap -- is up a more robust 13% in the same time. Even ...