**Like these.
Did they do anything other than magnify the users gestures? For instance, was it to draw attention to the fact that you smoked mechanically rolled cigarettes? It doesn’t seem that roll-your-owns would work with the holders’
What’s the Straight Dope?
2 Things I see immediately:
But mainly: it was what the “cool kids” did.
Since we’re in IMHO, I’d wager they kept one from getting nicotine stains on white gloves.
From a wiki:
They would keep your fingers from getting stained or from smelling like smoke, but I don’t think people cared about that much back in the day.
Ladies did. I was only a baby in the 60’s but it’s my impression that primarily ladies used cigarette holders, precisely to avoid nicotine stained fingers or gloves.
Very practical for non-filtered cigarettes. Spitting out flakes of tobacco was not considered cool at all.
Unless you also had half a jar of Butch Wax in your hair and a pack of Camel’s (straights, of course) rolled up in your sleeve. Then it was the height of cool.
Or so I read somewhere. Back before my hair fell out. And I stopped smoking. Or something. 
And I recall cigarettes sticking to my lip as attempted to pull them out of my mouth. What ended up happening is the smoke would stay put, my fingers slide down the cigarette at which point I would burn my fingers as I brushed the cherry off the cigarette and onto, usually, my pants. Or car seat.
Good times.
My parents used Denicotea holders with a cartridge that cut down on tar. It was a health measure.
BTW I smoked non-filter cigarettes for 30 years and never had a problem with tobacco flakes in my mouth.
Smoking jackets were apparel worn specifically to keep the smell of smoke off of clothes.
They have several practical uses:
[ul]
[li]Not getting ash all over your Dalmatian-skin coat[/li][li]Seductively blowing smoke in some private detective’s face[/li][li]Plotting against Moose and Squirrel[/li][/ul]
I smoke filterless cigarettes (manufactured, I don’t roll my own) and I’ve considered getting maybe a short stubby holder just to keep the tobacco out of my mouth. Plus if my lips are moist at all, the saliva breaks down the paper and it can come apart, releasing all sorts of tobacco shreds in my mouth.
But I didn’t want to be the guy using a cig holder looking all pretentious or whatever.
So you’re saying you didn’t want to be “that guy”?
In the case of Tar Gard it’s supposed to reduce the tar you inhale.
They were useful for signaling FDR’s mood. The higher the angle of the holder, the better he was feeling.