True, but this will not help you if have been asked for a search as they don't require solid evidence.. for example cop: "I believe you have drugs on you" "blar blar any bullshit reason can go here"
So they search you and find not drugs but a marker they can still pin you for this or at least try, the fact they originaly stated they were searching for drugs does not hold up for shit.
Bottom line is you need to be and confident liar/bullshit artist and never go back on your original story, or just say nothing apart from name address and so on. Don't fold no matter what they throw at you unless theres solid evidence the marker was used for graffiti they will be fine.
Your friend of a friend obviously has not learned this yet and he folds under questioning for a marker he could fold for alot more. In this way you can suffer for having friends of friends that are stupid.