The cigarette ends they leave in ashtrays are usually very short and smoked right down to the filter, and the paper of the cigarettes they smoke is often crumpled and stained wet. "Drug users always want other people to take drugs with them, for only then will they get a good supply," says Tsai Chen-nan.
吸海洛英的人更好辨認，他們在菸灰缸留的菸頭多半短短的，只剩下濾嘴；吸的菸紙則包得皺皺的，有水沾過的痕跡等。