Seriously good advice abovementioned....Or you like me never ever get them dirty...
I think the antique shop knives are the worst...they sit in a case for years having been placed there by the antique dealer who got them in well used condition....the gunk in the blade well and pivots solidifies with age...then I buy it and using the toothbrush, and matchstick method remove half a dead moose pelt worth of grunge...give it the washing up water treatment...papertowel dry and a bit of oil. Good to go.
The other thing Ive found are those nasty little spots of rust that appear on unused virgin blades in my collection...I use autosol for them...0000 steelwool for the particularly bad ones.
sounds like experience I purchased a used knife in antique shop in a coast city in Canada