I have a great many friends and clients in the fur business across the country. Some are trappers, trap manufacturers, trap designers, fur buyers, just a broad spectrum. The top trappers I know personally don't mind a canine trap not being dyed right off the bat. They do need to be free from grease and any odor.
Let air and water work on the metal for a bit and any dye you use will adhere better with wax.
Just my two cents. I have been catching fox for over 40 years and coyotes about that long. Clean and odor free is best. If the trap is covered properly an animal won't see it anyway.