Contrary to what most think bow tuning does not effect how accurate a particular bow is. Put one in a shooting machine and it will stack arrows on top of each other all day long if they are matched arrows. Tuning a bow can make it more forgiving however of form flaws that a shooter may have. Usually you are tuning the bow to you and the way you shoot. That's why you can't really have some one else fine tune your bow. They can do the initial set up however and usually be very close.
The book "Idiot Proof Archery" goes into detail about tuning myths and what actually effects what. Bob ragsdale also has his own web site if you care to look it over.
http://www.bowhunting.net/bobragsdale/ragsdale.html
The book quotes a few instances where they have had top archers attend the class (the book is a bit on the product placement side of things, but if you can look past that it's a good read) and when looking over thier bows have found them to be grossly missadjusted. Yet they were shooting near perfect scores? One case was where this lady had a two cam bow that was so out of time it had two valleys several inches apart. She never knew it because she didn't draw the bow that far to notice it.
That doesn't however mean someone should give up on the idea of tuning and it is worthless. It just drives home the theory that the archer is more important than the equipment. And keep in mind this is target related stuff. It's not overly hard to get a target arrow with adequate fletchings to fly well at 20 or 30 yards. Screw a broad head on and it's a whole new ball game! Tuning all of a sudden becomes more important.
I agree with the above, most robin hoods are just accidents in the first place. So of course you could do it with an out of tune bow. It's still pretty cool to see though isn't it.
Paul