From Wiki...

The Gila monster's bite is normally not fatal to adult humans (there are no confirmed reports of fatalities), but it can bite quickly and hold on tenaciously and painfully. If bitten, the victim may need to fully submerge the attacking lizard in water to break free from its bite.

I guess my question is where do you find pools of water in the desert to submerge a lizard that is latched on to a person? It is probably easier to find a dope smoking monkey in a tree to get the Gila Monster distracted.