Songwriting is a tough art, and one that isn't often given very much credit. Sure, there are people like Rufus Wainwright, Joni Mitchell, or Bob Dylan who often get credit for their songwriting; but usually it's due to the depth of their lyrical content.
And yet, there are some songwriters out there who - although they probably wouldn't like to admit it - write fluff when it comes to lyrics, and yet are absolutely rock solid with their songwriting skills.
Chief among them has to be Rivers Cuomo, frontman and songwriter for Weezer. This dude is incredible when it comes to writing a memorable song. The lyrics are totally disposable and are often simply a multisyllablic means for delivering the melody. But, holy hell, what melodies ...
There are few people who can write a melody that makes me addictively need to listen to it 8 or 9 times in a row. Mozart, Irving Berlin, Gershwin, John Williams, Michael Jackson ... that's the caliber of melody we're talking about. Something that worms its way into your brain on first listen and starts to replicate. Your normal thoughts and your internal monologue are soon dodging between notes of a tune that refuses to leave you alone and the only cure is to listen to the song again, which unfortunately merely continues the cycle.
There's something quasi-Sado/Masochistic about it, to be honest. But, damn if I don't enjoy torturing myself with a good melody. Truth be told, I'm extremely envious of composers and songwriters with that ability. Take a listen to Weezer's "Perfect Situation" to see the kind of thing I'm talking about. I couldn't tell you a single lyric in that song, and yet I've listened to it about 5 times already this morning just on the strength of the tune alone. It's really an exceptional melody.