I ran Morrissey's Palladium setlists through Excel (I know, I have too much time on my hands) and came up with this "rare setlist" of the tunes he played three or fewer times:

** SONGS PLAYED THRICE **
Ganglord
Human Being
I Just Want To See The Boy Happy
In The Future When All's Well
Jack The Ripper
Last Of The Famous International Playboys
Let Me Kiss You
Life Is A Pigsty
Please, Please, Please Let Me Get What I Want
Shoplifters Of The World Unite
The National Front Disco
The World Is Full Of Crashing Bores

** SONGS PLAYED TWICE **
Disappointed
I Will See You In Far-off Places
The Boy With The Thorn In His Side

** SONGS PLAYED ONCE **
Everyday Is Like Sunday
Girlfriend In A Coma
Good Looking Man About Town
Last Night I Dreamt Somebody Loved Me
Lucky Lisp
The Youngest Was The Most Loved
Whatever Happens, I Love You
You're Gonna Need Someone On Your Side

On the other hand, the most played songs were:

How Soon Is Now? (100%)
Sister, I'm A Poet (100%)
Tomorrow (100%)
Why Don't You Find Out For Yourself? (100%)
First Of The Gang To Die (88%)
Stop Me If You Think You've Heard This One Before (88%)
Stretch Out And Wait (88%)
All You Need is Me (75%)
Billy Budd (75%)
Death Of A Disco Dancer (75%)
I Like You (75%)
Irish Blood, English Heart (75%)
One Day Goodbye Will Be Farewell (75%)
The Loop (75%)
I'm Throwing My Arms Around Paris (63%)
That's How People Grow Up (63%)
Dear God, Please Help Me (50%)
London (50%)
You Have Killed Me (50%)

He played 42 different songs in all -- and an average of 21 per night.

It looks like the second, fourth and seventh nights had the "rarest" setlists, with 9 of the rare songs played.

The third night was the "worst," with 20 songs played, only three of them "rare."