Even though there isn't a disco ball in sight, all of the motifs in All the President's Men root it firmly in its time of the 1970's. Cigarette smoking isn't nearly as prevalent today as it was in the 70's, when people smoked not just in the workplace, but also in the elevator to the office.
If you travel back in time to the 1970's, bring a gas mask.
Two major characters smoke like Katniss Everdeen's fire dress. One is Deep Throat, who smoke so much, he inspired the famous Cigarette Smoking Man character from The X-Files. His smoking creates a pretty sinister air: he's cloaked not just in darkness, but also in smoke.
The other person sure to come down with a nasty cough is Bernstein. Woodward, who doesn't appear to smoke, even comments on how Bernstein smokes everywhere, even in the office elevator.
Bernstein's smoking isn't done to make him villainous, like Deep Throat. It's more used as comic relief, and to give us more contrast between Woodward and Bernstein, like Oscar and Felix from The Odd Couple. They're an odd couple, indeed.