Guinea will run up to the side of her cage when she hears me coming, just so she can lick my fingers! Sometimes she'll lick my nose too, but I'm not sure if it's always because of salt. Even if I just washed my hands she'll still lick me! I think it's more out of affection than anything else, since guinea pigs have been known to lick each others ears to groom them, but I've heard they only do that if they're close friends. Maybe this is the people version of that?
It's funny, if I'm trying to give her a carrot she'll nudge the carrot out of the way and keep licking my hands! It's nice to know she cares more about licking me than eating carrots haha