The trouble is, you can't look at the city status screen until after the occupy, enslave, exterminate decision is made.

You can send a spy in before besieging the city. That will tell you the "official" religion and the "contentment" level, but so what? You often run into cities that are "officially" pagan but predominately Christian.

Sometimes, if the garrison attacks you and you take over the city without initiating the attack, you can't even look to see if the city has a red, yellow, blue or green "face."

This "life or death" situation is made without the relevant information. I wish you could check the city status screen, then decide its fate.