Hooks are one of the cheapest items in carp fishing, yet they are responsible for the final connection between you and the fish.
That is why I have never understood anglers who try to get every last bit of life out of them.
Rust is a good example.
A tiny surface mark does not necessarily mean a hook is about to snap, but once corrosion starts, I begin losing confidence in it.
Hooks are repeatedly exposed to water, silt, salt from bait and moisture inside rig boxes.
Even premium hooks are going to deteriorate eventually.
The point is more important than anything. If rust affects the point or barb, the hook is finished as far as I am concerned.
I also do not like reusing hooks after catching fish if the point has dulled at all.
Considering a packet of hooks costs less than many anglers spend on one bag of boilies, replacing one seems like a pretty sensible insurance policy.
I know some anglers sharpen hooks repeatedly and use them until they physically cannot anymore.
Personally, if there is any doubt, I change it.
What do you do with hooks showing a little surface rust?