Xenoanthropologists concluded that Sand People were just jerks. One, Dr. Daniel Jackson (no relation to the one you're thinking about) concluded specifically that they suffered from "Sandy Crotch Syndrome" or SCS. Symptoms include decreased verbal skills, an obsession with Michael Jackson songs among the males, freebasing, delusions, and suicidal tendencies. Eventually they get so fed up with having sand in their crotch they jump out of planes to transfer their souls to a body without SCS. Unfortunately it results in their own death and the victims death depending on their aim.
Sand People torture was not, in fact, the torture of Sand People—though that might be kind of cool—but rather, the type of torture inflicted by Sand People upon their captives but it still pwned. It was distinct from most other methods of torture in that it had no discernible goal and was never accompanied by interrogation, or indeed any commentary more sophisticated than "Hhhrrrrnnn! Hrn-hrn-hrn-hrrrnnn!" An alternate version existed in certain tribes which involved dropping Sand People on the victim from twenty miles in the sky (kilometers suck). The most harmful method was forcing their male victims to listen to Michael Jackson sing. There were cases of the Sand People doing other stuff to people as well, but none have been confirmed.