Hey Daniel, thanks for the question.
First off, I want to preface this by saying that any musician that tells you a song is only good if it’s lyrics are deep, or a song is always bad if it’s lyrics are simple, is wrong. Music is a matter of taste. I love pop music, always have, and some of the best written and catchiest pop songs are incredibly simple lyrically. That doesn’t mean they were easy to write though. Pop is an art form just like jazz, ragtime, classical, soul, R&B, etc. In fact the roots of pop come from jazz.
There really isn’t a “correct” answer to this question, because the meaning of a lyric is always in the eye of the beholder, but I’ll give you a couple examples.
Here is a sample of the lyrics for Justin Bieber’s “Baby”… which was a massive hit, and I think a brilliantly written pop song:
Ooh whoa, ooh whoa, ooh whoa
You know you love me, I know you care
Just shout whenever and I’ll be there
You are my love, you are my heart
And we will never, ever, ever be apart
Are we an item? Girl quit playin’
We’re just friends, what are you sayin’
Said there’s another, look right in my eyes
My first love, broke my heart for the first time
And I was like baby, baby, baby oh
Like baby, baby, baby no
Like baby, baby, baby oh
I thought you’d always be mine (mine)
Baby, baby, baby oh
Like baby, baby, baby no
Like baby, baby, baby ooh
I thought you’d always be mine
Those would qualify as simple. I hesitate to use the word “shallow” because it has a negative connotation, and a bad song is different than a simple song. That would qualify as the latter.
Next is “Helplessly Hoping” by Crosby, Stills & Nash. These are what I would call “deep” lyrics:
Helplessly hoping her harlequin hovers nearby
Awaiting a word
Gasping at glimpses of gentle true spirit, he runs
Wishing he could fly
Only to trip at the sound of goodbye
Wordlessly watching, he waits by the window and wonders
At the empty place inside
Heartlessly helping himself to her bad dreams, he worries
Did he hear a goodbye?
Or even hello?
They are one person
They are two alone
They are three together
They are for each other
Stand by the stairway, you’ll see something certain to tell you
Confusion has its cost
Love isn’t lying, it’s loose in a lady who lingers
Saying she is lost
And choking on hello
I think the difference in definitions comes from how easy the song is to interpret. “Baby” is pretty easy to figure out. He’s singing to a girl that he wants to feel for him the same way he feels about her.
“Helplessly Hoping” is like a painting or a poem come to life. It could mean a lot of different things, or be about a lot of different things. The word harlequin has a lot of varying definitions and uses, but it is one of my favorite words. I picture this song as being about a man singing to the ghost of his lost love, hence the “harlequin” imagery, but it can be taken a lot of different ways.
Anyway, I hope that makes some sense. In my opinion, there are ways to write proper song forms, and ways to present lyrics in a method that makes sense… that’s what can make a bad song or a good song, but good lyrics can be simple, and vice versa.
Thanks! I also offer personalized advice and answer questions about the music business plus give constructive song critiques.