How do you use "poner verde" and what does it mean?
The example is: No te molestesen leer el libro: la crítica lo (poner) verde.
What does "poner verde" mean, and when do you use it? With people? Or is this sentence referring to the book?
You use when something or someone talks bad about something or someone ^^
Le puse verde "I talked bad about him"
In your example, "No se molesten en leer el libro: la crítica lo pone verde" means "Don't bother in reading the book: the review talks bad about it"
Welcome to the forum!
"verde" can also be used to indicate that something is obscene.
It can also be referring to putting a "tick" (green) during an election.
"El verde lo pones tú." Something like "you decide when you put your tick".
It can also mean to insult someone.
criticar=to review (art, literature)
with that in mind, now read discussion below.