Most VN Era M67's that I have examined have shown "sloppy" nomenclature markings to some extent. The attached photo shows an original '67 with typical uneven / smudged lettering.
I believe that the main problem with this auction is that close examination of the description and photos raise(s) more questions / suspicions then are answered.
Nothing against the auction grenade or seller, however I would have presented this grenade differently for premium bids. The storage container / packing and later style safety clip offer nothing as a sales feature and just give a potential bidder an understandable reason to be skeptical and begin looking for, or foreseeing other potential / unforeseen problems. Also from the description and photos given, it is not possible to determine if the fuze lever is of the proper era for the body without further investigation / correspondence. It only takes on red flag to chase bidders away from an item and or the seller without further interest.
Some high quality photos of the grenade on a neutral / blank background, along with photos of the fuze lever nomenclature would be the best tactic. I always try to include 8 - 10 total photos of an item from many angles and macro setting to tell the true story on condition and let the item sell itself (Or not).
Again nothing against the grenade or seller, just that a first class presentation is in order when auctioning a premium piece for a premium dollar.