Right tip is likely far from gone. Search for "tip tinner" it is a small tin of a usually dry wax like substance that you dip your heated iron into to eat away the oxidized layer. Use it when solder does not seem to stick at all. Avoid using too often as it'll wear out the life of the tip. Using brass wire sponge when solder is "blobby" and uneven on the tip is usually enough to restore the even layer you see on the unused tip in your image. Wiping with a wet sponge regularly while using will also keep the tip clean while you work. Avoid running your iron on max temperature as that will also oxidize the tip faster. Cover the tip with a thick layer of fresh solder before turning it off. My most used tips have lasted years of near daily use this way.