Now Lefty he can't sing the blues
All night long like he used to
The dust that Pancho bit down South
It ended up in Lefty's mouth
The day they laid old Pancho low
Lefty split for Ohio
Where he got the bread to go
Well there ain't nobody 'knows

Good Lord, the meaning of this is obvious! It's a Marxist tragedy!

"Lefty" is obviously an old Socialist, a member of the political Left. "He can't sing the blues" because he abandoned the Revolution and went to Ohio, which everyone knows is about as bourgeois a state as there is in the Union but he was probably bought off by the Capitalist Oppressors Of The Workers ("Where he got the bread to go...."). Pancho is symbolic of all of the workers of the world, a la Woody's "Deportee" song. Lefty is responsible not only for the death of the Revolution, but for the death of the workers (the "Panchos") and when the Workers "bit the dust" is ended up in Lefty's mouth because Lefty was responsible for it all.

Viva Che! A La Pared Con Los Tradores!