Are they rusty? Quality blades would be of stainless steel I think so I don't think the passage of time should have had too much impact.
"Quality blades" (however you wish to define them) are available in both plain carbon steel and stainless steel. Junk blades are also available in both plain carbon steel and stainless steel.
E.g., HD Sports (Wilson and MK) produce some of the most highly regarded blades. But only the Wilson Phoenix has a runner fabricated from stainless steel. All their other blades (such as Gold Seal, Pattern 99, Coronation Ace, Gold Star, Phantom, and Professional, including traditional, Lite, and Revolution models) are fabricated from plain carbon steel (or have a runner fabricated from plain carbon steel for Revolution models).
Other major blade manufacturers (Jackson Ultima, Riedell Eclipse, Paramount) offer both plain carbon steel and stainless steel versions of their top blades,