Originally, this was going to be a suggestion to allow people who smoked and frequented a specific bar (or even worked there!) to have a matchbook from that bar in their house or on their person, etc. The idea would be to give us investigators a lead into what haunts they frequented, however as I was writing this out I thought, "What if the murderer accidently left something (say a matchbook with a bar's name on it) at the scene of the crime instead of just their specific calling card?" It would be an interesting lead to follow up on, and could end up with the investigator deciding to stake out the bar or even break in to check the CCTV footage.
What do you lot think about this? Good idea, bad idea?