Very, very, diffficult question to answer! And totally subjective, I think.
For me, it has to make me feel. It doesn't matter what, but I want to listen to a song and be moved one way or another - that can be moved to tears, or moved to a state of happy, mad excitement.
Also, although I love deep, multi-meaning lyrics, I don't actually believe that a song has to be really wordy and clever or overly poetic; sometimes it can be simply the voice that will move me, or just the music.
My taste is so eclectic song-wise - everything from Queen to Dylan; Radiohead to Abba; Lennon and Mccartney to Dusty Springfield...the list goes on and on! And I absolutely abhor music snobbery - those that state you cant like this or that as it's just not fashionable, dear, or it's just not profound enough. Everything has it's place - when I wish to hear stories I'll delve into Dylan; when I want an emotional vocal performance I'll dig out my dear old Queen records (Freddie mercury, imho, was a vocal genius, and his earlier song lyrics were completely original and unique - Seven seas of rhye; Killer Queen, etc.).
Anyway, I could go on but I fear I have already lost most of you due to the length of this bleedin' post! lol.
I'm Paul, btw. Nice to meet you all.