I've noticed lately that alot of the lyrics I like, despite the 'obscure' nature of some of my fave lyricists (Bob Dylan, Tom Waits, Jeff Mangum - same guys everyone likes) are just real simple aphorisms that i can't imagine phrasing better. Right now its Springsteen - 'Motion is emotion and a motion deep inside/and it ain't no sin to be glad you're alive'. I can't think of a better way to express that, or a reason that thought shouldn't be expressed. Same with Craig Finn: "Lost again in love and faithless fear/i've had kisses that make Judas seem sincere". Its plain language, and the only allusion is pretty obvious. Or Neutral Milk Hotel: "How strange it is to be anything at all". They're simple statements of simple universal truths, and their simplicity is their beauty.
As for obscuring it... i've read interviews with Joanna Newsom about her new record, and she says everything in it has a very clear meaning to her, though it appears obscure to others. Her sister is an astronomer in New Zealand, so all the lyrics about the stars and meteroites and meteroids relate to that... and certain things relate to her lover and her relationships. Its all quite simple to her, but it needs unpacking for us because we don't spend all our time in her head, and not all the symbols are obvious. If you've got anything like that, then its easy- private nicknames for things, abbreviations for streets, whatever.... I could write "I've gone from THC to THS to QC", which would be a shitty lyric... but would simply mean I went from smoking pot to listening to The Hold Steady to reading Questionable Content. To use a more obvious example, Craig Finn's allusion on one of the b-sides: "I'm listening to track 3 on John's last CD/gonna make it through this year if it kills me, and it almost killed me" is pretty obvious IF you know the Mountain Goats song he's referencing and that the Mountain Goats are a dude named John. On the same token, reading Milton for a class made me realize that certain lines of Nick Cave's that i thought were original were actually direct quotions from Paradise Lost....
You can get real obscure with it- get into total personal symbol-systems, mythologies, whatever. William Blake did alot of that, and Dylan's got a bit of it.... when i write i tend to take things from Dylan songs, which is pretty obvious and overdone