Some frogs that is...most are absolutely harmless (when you're talking about psycho-actives); the possibility of water-based diseases...that's another story. It all depends on the 'site-specific' watershed/river drainage basin...For instance...being here in the Ohio River Drainage Basin...I wouldn't lick one for the wide range of pollutants and the fact that some cities along the tributaries have a tendency to have older sewage systems that when a flood-causing rain comes...the sewage system is linked with the storm drainage system...thus...sewage sometimes spills out as a result.
The largest one (Lithobates catesbeiana) American Bullfrog is the largest in the US...but toads on the other hand can get much bigger (on average) than frogs....but with you being in the Great Basin area of the Southwest...lizards/snakes/skinks/etc are the major herptiological species out there...so don't worry.