This part is definitely accurate. It is also true that on some items date codes are very difficult to spot (SLGs in particular).
The total absence of a date code (if the item was made after the 80's) is indeed strange, but the presence of a date code doesn't mean the item is authentic.
To find the date code in your Delightful slip your hand in the pocket and feel along the side seams, once you feel the leather tab, gently pull the pocket inside out to get a better look. Your SA was correct though; date codes are intended for internal use (used to track batches as well as individual items sent off for repairs) and are in no ways intended for authenticity. Every once in a while a bag will escape the warehouse without a date code, but any good authenticator will be able to overlook that when determining whether something is legitimate or counterfeit...make sure to mention this to any prospective buyer should the time ever come if you want to sell.
That's because the code is stamped directly onto the alcantara lining. Unfortunately that material has a tendency to relax and fluff back up over time and with use, especially if the bag is frequently used and the its contents tend to rub up against the stamp.The date code is barely visible on my Artsy!
The date code is located on a small leather tab inside the zip pocket of my delightful and mine was MIF. Vintage Vuittons may have slightly different date codes.
