I clean infrequently, but I also don't have folks eating at the table either. *
I oil my CPCs once they arrive, but they don't need much beyond that. Just playing with the chips keeps them looking fine (finger oils and such). There's a camp here of folks who never oil, so it's really personal preference.
[* Ages ago, I had a player come to my game with a bag from Jack-in-the-Box who proceeded to eat his burger and fries while playing. He was using a napkin and was good enough to wash his hands after, but the damage was already done. I had to wash the cards that night once we were done. The chips had come to the game in a cage, and I didn't have a chance to put them away after I got home. I had to leave town for work and when I returned and opened the cage less than a week after the game, everything inside reeked of fry oil and burger. I had to do a full wash and re-oil on the chips at that time. I also implemented a "no eating at the table and wash your damn hands" rule, and haven't had a problem since.]