New traps have a thin coat of oil/grime on them. Traps will rust quickly in the ground, especially if you use salt as antifreeze when making your sets.
Typically traps are boiled to remove the oil & odors, then allowed to rust a little to roughen the surface, then boiled again in logwood dye basically Bluing the metal similar to a gun to give it some rust protection. Traps are then dipped in melted parafin wax to give a little more protection, and lubricate the trap to help it fire faster and not stick in your set as much when you get rain/ice/mud.
Alternative methods involve some commercial products like SPeed Dip or some of us lazy guys just clean and spray paint them.
When your traps get contaminated with scents from catches, bait/lure, you, oils or anything unnatural, your target species can avoid your set, dig up the trap, or otherwise not work your set properly, you will want to boil or clean your traps again to get the smell off.
If you go the paint or speed dip route, plan on a week or more of dry time to let the paint smell evaporate.
