What makes a good opening trap?

Playing for tricks in the opening isn't always the best use of ones resources. For every checkmate that begins with 1.e4 e5 2.Qh5, there are a number of games where such 'direct' play gets punished by more experienced players.  So choosing which opening traps you aim for often depends upon a few different factors.
My first (purely subjective) criteria is: How often will I see this opening? No good finding a particularly clever idea against the Dutch Defence if no one in your chess circle plays it. So traps in the Ruy, or the QGD probably have more value than traps on the black side of the Solkosky.
Secondly: Are the moves leading up to it plausible for my opponent? As any chess coach will tell you, don't reply on your opponent playing bad moves. Sure, some moves may only become bad after the right reply, but moves that seem sensible are more likely to be played than those that are not.
Thirdly: Do I still get a good position if my opponent spots the trap? This is about having it both ways. If the trap is sprung, fantastic, but if not what happens next. I had a situation like this in Gibraltar, where I could play a trappy move, but the right reply would see me in a worse position. I decided against it.
Flicking through one of my books on opening traps, I realised that there were only a few entries that passed all three tests. Some failed the 'length' test (the later in the opening the less likely it is to occur), while others relied on the opponent missing the correct refutation. But there were still a few that were a little new to me (albeit borrowing from traps in other openings). The one I've chosen to show comes from the Two Knights Defence, and is based on presenting White with an unusual variation, increasing the chances of a mistake. 6.d6 is obvious, but the start of the problems, while 7.Nxf7 is the big mistake. In my database there have been 62 games after Nxf7, so it still catches lots of fish.


Victim - Trapper
Anyclub, Australia