At least in the United States, smoking is something fewer and fewer people take up these days. This obviously wasn't the case back in the 50's through the 80's, where cigarettes were commonly smoked out in public.
So whenever I see a period movie or show, filmed in the 2020's but taking place in the 60's, there's frequent scenes where characters are smoking cigarettes in a bar or stress-smoking to the filter after a stressful conversation. And I think to myself, "are these actors all smokers? In this day and age? Or is that an unlit prop ciggy with VFX smoke done in post?"
Are fake cigarettes common in film production now, or are these still typically the real deal?
They don't inhale. You can usually tell the real smokers from the ones who don't smoke if you watch the exhale.
If it all comes out in one puff, they aren't smoking, just holding it in their mouth.
If it comes out in a long stream or through thier nose, then they are likely a real smoker.