There was an OC only meme last week. It got a few handfuls of people to tag in, but not many people tagged around. I think I'd be more open to an OC friendly meme as opposed to a strictly OC only meme. People seem to feel uncomfortable bringing attention to their OCs in a meme like that, but I think maybe if there was a meme that had a 'Get to know (x)' and you had to have your top comment be a little blurb about the character, canon or OC, that might be something that gave people a hint of writing styles and if the person had a good grasp on their character.