Note: remains of small groups of Persian soldiers have indeed turned up, and none of them AFAIK show any sign of death in combat. Also note that the archaeologist claims that it’s not possible to die in a sandstorm, a claim that is ridiculous on its face. It’s unlikely that an entire 50,000 man army will be found in formation buried in the desert — it’s perfectly reasonable to figure that zero visibility led to groups of various sizes going off in various directions. Also, given the details in Herodotus’ account — and we know that he was basically always reliable as a reteller of what he hear or a when he described what he saw — suggests that a small number of survivors managed to return to make report, and that’s not surprising at all.
http://www.freerepublic.com/tag/cambyses/index
Having read the account of Alexander’s troop march home from the Indus through southern Persia, I can totally believe that.
Quite true but skepticism arises from the fact Herodotus was a "reteller". He honestly wrote down what he was told but never checked to see if what he was told was true. Still, a great historian given his times.