I have some nice healthy calluses. They do tend to flake and bust up here and there but I think thats natural with balls of dead skin on the tips of your fingers! There is always some toughness underneath as a base but the outermost skin goes through cycles! I wash my hands a lot with work and notice that when my hands are constantly getting wet my skin will soften a bit...or have some effect on the calluses. I play mostly acoustic. A friend of mine for whatever reason rarely changes his strings and wow does that hurt! Keeping some fresh strings on your guitar is a benefit!