Patina
It doesnt really apply to items like lamps (unless they are brass or silver etc) the little nicks and signs of use your lamps has are all good signs of a vintage piece and certainly nicotine or grease etc are worth removing.
Nice lamp!

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Patina/grime in the Louvre
As I read this thread yesterday, I thought about another tangentially related recent story to do with "patina/grime"... the moral here being applicable to Design Addicts too. Clean by all means, but don't overclean!
http://www.guardian.co.uk/artanddesign/2011/dec/28/louvre-leonardo-overc...

Therein lies the rub.
Unfortunately, it happens all too often.
Thanks for the link!