How to tell if someone is a smoker?

Have you ever wondered how to discern whether someone is a smoker? It's not always as straightforward as seeing a lit cigarette in their hand. There are subtle clues to observe, such as the scent of tobacco lingering on their clothing or breath, the slight yellowing of their fingers and teeth, and even their choice of activities and social circles. But be mindful, not all smokers are the same, and some may take measures to conceal their habit. So, what are the most reliable indicators to determine if someone is a smoker? Let's delve into the matter and uncover the truth.