This has not been a yes or no question with respect to chip cleaning. I do clean SOME chips that have slight oily grime (crud) on the surfaces. Presently, it is a personal decision one makes based on asthetics which remains a choice for the owner to make. An uncleaned chip can always be cleaned at a later date if the new owner wants to do so. It is very difficult to restore a cleaned chip to the original condition it was before cleaning.
Up until now, there has not been a great magnification in price between a cleaned chip and an uncleaned one. The reason cleaning is taboo in the coin hobby (industry) is that a gem uncirculated coin with no visible signs of cleaning (lack of circular swirl marks on the surface of a prooflike silver surface for example) makes the coin much more valuable than one which has been cleaned. Some folks mistakenly believe that cleaning coins inproves the grade (condition). It does not. Wear is wear. Same is true with chips. If the chip is worn and has rounded edges, no amount of cleaning will make it look like new. This should not be a concern with chips as chips do not have the mirror-like surfaces such as silver/gold/copper/nickel coins exhibit. Unfortunately there seems to be a growing movement among some dealers who are pressing for grading of chips... and with grading comes different price levels. I am aware of the differences in opinion on this subject.... however, the same chip in six different grades?? What one dealer's grade of XF (extra fine).. will become another dealers grade of UNC (uncircluated... with a little bit of help from a bottle of cleaner). That in itself is bad enough, but when the price of an XF is re-priced as an UNC at several times the price of an XF... not merely a few dollars over the price of XF, is the time this hobby is doomed.... in my humble opinion. Keep your eye on developments on this issue. It is critical to all of us. If we, as collectors, allow this to happen.... shame on all of us. Archie