Free DLC Steam Code Giveaway for Villagers and Heroes (Plus More!)

Yes, but if they aren't careful, they might mark it as recieved and get banned.

That's why you should mark as not received. If you mark as received and don't activate, that's against rules.

Steam should have an option to check that :(

Actually DLC can show up on profile. (and Villagers and Heroes: Hero of Stormhold shows).
Then there's API (appuserdetails), but it only works for friends. :P