Actually, I completely disagree with this idea. I think that given the opportunity, white sharks will follow up (and
have followed up) on that initial bite by consuming a person.
Think of this in terms of their hunting strategy. One massively powerful bite, the prey bleeds out and dies, and the shark returns to finish its meal.
In most countries, people rarely surf or dive solo. In Chile, however, these activities have been commonplace, particularly when diving for abalone. In the U.S., there's typically a "buddy-system."
So in most countries, it happens like this:
1) Initial bite/attack.
2) Shark hangs back.
3) The diver is helped/removed from the water.
In countries like Chile:
1) Initial bite/attack.
2) Shark hangs back.
3) No help for the victim. Victim bleeds out/dies.
4) The shark returns to feed as if it had attacked, say, a seal.
I'm of the opinion that we're a
perfectly acceptable meal for a white shark, even if the initial attack is a case of mistaken identity. There are many cases where the shark has
returned to the victim and consumed the remains, and there are many divers that have simply gone missing...
The explanation that we simply aren't appetizing to white sharks was an attempt to explain the initial bite and apparent abandonment. However, with an understanding of their hunting strategy (as you yourself have explained) it seems far more likely that it is a normal hunting behavior. Observed behavior after attacks have indicated that the shark doesn't actually leave. It goes to depth and waits in the general area.
They may have other ways of "feeling" out their prey as well.
Before many attacks, people have reported feeling something "brush" up against them under the water. Typically, they describe it as a slightly abrasive feeling, but most often there's no actual (or perceived) pain.
For anybody unfamiliar with shark anatomy, their skin is covered by tiny "teeth" called denticles. These can be highly abrasive. For this reason, shark skin is used as a sort of sandpaper by many tribes of Pacific islands.
Well, last I heard, there were tiny receptor organs/structures discovered underneath dentacles on the heads of some sharks. In form and function, these resembled
taste buds.
It's not entirely outside of the realm of reason to postulate that by "rubbing up" against their prey in a slightly abrasive fashion, perhaps out of curiosity, they can
taste it, especially if they induce small-scale bleeding.
Again, I haven't kept up with that, but needless to say it's a bit creepy and a LOT awesome.
But thanks! 
t:
