Yes, usually by the smell, colour of their teeth, nails and sometimes by the typical "smokers cough"
Although this would mostly be the case for long term heavy smokers as not every smoker would be the same.
My personal opinion, I don't find anyone who smokes attractive at all, I find it a big turn off.
Smoking is an expensive and hazardous habit that most get addicted to and I would not want anyone I love and care about to be caught in it's vicious cycle with the risk of dying prematurely.