Its really not hard to notice hairline fractures. Most of the time you can simply run your finger nail along the inside of the bore where the wrist pin sits and you will feel the crack. Otherwise you can use a fine haired paint brush (done this before) and the hairs will catch in the crack.

There are many ways to identify fractures.

Btw didnt say you didnt know anything so the sarcasam really isnt necassary. The job is easy to identify as long as you pay attention to detail but Im sure you knew that already.