I would think it's just a visual reinforcement of someone's imagination.
Perhaps you would like to see the Queen of England sucking a black cock.
You can imagine it, but it might fire your imgination a bit more if you saw her faked.
That's my take on it anyway.
I agree with Whammer with the fakes also there might be a few people out there that set around looking at a picture of a person as the Queen as Whammer said or maybe a girlfriend or actress that they have these sexual dreams about and set and look at the fakes and cuff the old mule. Sexual Dreams and fantasy. Thats my thought
I wonder this myself...I don't think anyone would care if these people just said..."hey, we're not looking to hook-up, we're just into the idea"
I could respect that, and would probably be willing to help these folks enjoy their fantasy.