That's a pretty close description. It has been pretty popular in Toronto, especially in the Jane and Finch area. Lots and lots of people are carded.
http://www.thestar.com/news/gta/2013/11/18/carding_by_toronto_police_drops_sharply.html
I don't know when DM was carded and the MSM reports all seem to just say a "physical feature", but AB claims it was his tattoo.
http://www.annrbrocklehurst.com/2013/11/dear-readers.html
Thanks for the link, AD. Gosh, if LE jots down all the tattoos sported by everyone they "card" it would take them all day to fill out the forms on MWJ, for instance, or most of his friends. Anyway, for some reason, we're given to understand that note was made of this particular, rather modest tattoo. Yes, the tattoo! That amazing disappearing/reappearing tattoo. Sometimes on one arm, sometimes on both, sometimes with a boxed border, sometimes with none. The RBEG noticed the tattoo on the wrist of a test driver who wore a short sleeved orange shirt. I don't know the protocol for meeting tattooed people for the first time. Do we establish eye contact or do we read their tattoos? Let's presume it to be rather uncomfortable to be reading a stranger's body unless there was an opportunity to do so unobserved. Sort of like sneaking a look at your watch when the luncheon speaker is boring. If so we can presume this tattoo was on the right wrist, i.e. the one nearest RBEG as passenger enabling the RBEG to read the tattoo as presented with DM's hands on the steering wheel. However, the word is then upside down. Can you correctly read the word "Ambition" upside down?
By the next evening, one of the test drivers who arrived at the Bosma household also wore an orange shirt, but this time it was long sleeved and night had already fallen, so it is unlikely, even improbable that SB could have seen this tattoo. MSM and early LE reports seem to fudge the issue. It's never stated that she saw this tattoo, or least not in any article I have found.
Nevertheless, it appears undeniable that DM has a tattoo "Ambition" on his arm.
Here's a photo, showing a eensie little something rather high on the left wrist. It does not appear to be enclosed in a border and IMO it is not positioned where men usually wear wrist watches, and it is not on the right arm. Maybe someone has a better image, this one being rather unreadable, IMO.

I find it very interesting that Hamilton LE had early and immediate access to Toronto LE files sufficient to pull up every notation of the name and address of anybody with an "Ambition" tattoo in the two large metropolitan districts. Given that this appears to have been the case, it follows that DM is the only person in the broad area who has such a tattoo.
By the way, anybody with an indelible sharpie can create a reasonable facisimle in the off chance, just for example, that they wanted to impersonate someone who has the word "Ambition" tattooed on their arm but they don't know exactly what that tattoo looks like. That's part of the reason I find the eyewitness description so potentially relevant as expressed in the poster LE released at the time. It's because it seems to differ significantly from the tattoo DM actually has (although it is on the left arm.) Is this LE drawing based either on the RBEG's description or on the carding report.
Whatever the source it does not appear to look like DM's tattoo. IMO. IMHO. Are other people seeing something I'm not?