I share my collecting with my kids and they had fallen in love with the New Zealand coins circa WII.  They have especially taken a liking to six pence silver coins and we collected more than a few and sent them off to be graded by ANACS.  What returned was that many of these coins had detailed grades, which suprised me.  I've gotten pretty good at recognizing when coins are cleaned, at least in the US series.  The 50% silver mix and the history of these coins seems to have thrown me off as nearly half of them have returned detailed cleaned.  We've been told that is is hard to get such series in decent condition from NZ withouth them being treated to polishing agents and harshly wiped.  Alought, looking over the coins, I'm not certain what to look for in terms of signs of cleaning.  Needless to say, this is a new learning curve.  In a few weeks, the NY Internation coin show will being coming into town.  I hope to get a crack at a few new NZ Six Pence coins at that time, and have a chance to discuss when we have at this point learned with real experts.