Having rust is fine though, it's just oxidized iron. Sure it won't look pretty but it's largely harmless in food. The main caveat I've seen is when making acid

Having rust is fine though, it's just oxidized iron. Sure it won't look pretty but it's largely harmless in food. The main caveat I've seen is when making acidic foods with iron cookware (cast iron or carbon steel) it may affect the taste ever so slightly as some of the acid is reacted and takes off the top layer so you end up with a "stain" that looks like the food. Still just cosmetic only though.