How To Tell If A Coin Has Been Cleaned, Dipped, Or Retoned

A cleaned coin normally has minute parallel or circular scratches on the coin , Most noticed in the fields.
A dipped coin is usually lustreless and slippery to the feel, However there are some dealers that know how to "Mini Dip" coins without destroying the lustre But they still have that slippery feel about them.
A dipped and re toning coin will show little if any evidence of original lustre and look "Off".

Having said all this , a great deal of our older pre decimal coins have had the odd touch up in the past because it used to be accepted practice

You can't tell from Noble's photos, you need to view in person.

Something which will surprise you is the most common form of cleaning on Australian coins is mechanical cleaning (e.g. wiping/brushing/etc). This will leave parallel hairlines in the exposed fields which will be evident under a very bright light against a contrasting background (e.g. one bright lamp in a room with otherwise low ambient lighting). Lustre will also be dulled or absent (depending on the extent of cleaning) on the cleaned regions so if lustre is dull considering the grading, you should take a closer look.

Dipping removes toned metal off the coin and leaves residue on the coin, both of these dull the lustre. It's difficult to describe this effect, it's something you'd really need to see in hand but I've written about the causes of this effect here: http://www.numismatics.com.au/Blog/...nding_Lustre