![enter image description here][1]

In the above Image edit was suggested by unknown user. That edit seems to be not spam and related to user Question. But I dont know whether OP has tried this or not because It was posted with unknown user name.

what I am thinking is , how about one more option that asking the editer as " are you the original user who posted the Question " ?

Pros:

• so that we can believe that the user tried this also with out any doubt on the editor and The answers can be more effective.

Cons:

• what if spam posted and clicked as original user ? 
  

solution:

• what ever the edit it is should come across the Review/ Suggested Edits. So we usually catch it and going to remove it.

Just a Suggestion ,decision is yours. [1]: https://i.sstatic.net/49bgD.png