It's a rule of thumb: Let people create things, and you're definitely going to see dick drawings. You might even see Nazi doodles, too. But Battlefield 4 is fighting that.
The game is currently in beta, but there are already Nazi emblems popping up in the game (see above). Yes, that's rather icky! However, not everyone is using the emblem tool to create unsettling flags for their helicopters, vehicles and clans.
As documented on Reddit's BF4 page and its BF4 emblems page, beta players are creating their country's flags, pop culture images and more. It's much nicer to see people using the emblem tool to create stuff like this.
Racist Emblems Already Appear in Battlefield 4 [BF4 Central -- Thanks James!]