I agree, photos with people holding up a piece of paper are not worth much as a proof. Actually, they can do more harm than good, as they create baseless trust.

Instead of trying to prevent impersonation, I'd suggest promoting truly original input and ignoring unoriginal, unless it's some kind of news and it's clearly marked as a re-post, like this one for example.

I think Google is reliable enough so that a content's originality can be verified by running a search on a random fragment of the text. This is what I do if I find a post worthwhile and the content claims to be original (i.e. there is no link supplied):

• I upvote, if Google search shows nothing by Steem.
• I don't upvote, if Google search shows other sources and there is no proof that the Steem account belongs to the original author.

Also, I think that if you are a good content creator, you should be able to create an introductory post on Steem that confirms your writing skills. If you don't want to bother with that, you are probably a fake.

To sum up: let's not fight with impersonations, instead let's concentrate on promoting original content and clearly marked re-posts.