I bought exactly the same item ('onewash' 501's) 8 months ago from Amazon using the same webpage.
However the 501's that arrived this time round are made from a much thinner denim and are of inferior quality to my earlier purchase.
They're also made using two contrasting colours of thread for the stitching.
This is most noticeable across the back pockets, where whiteish yellow thread is used for the Levis 'v' motif, clashing with the traditional orange thread that the pocket is actually stitched on with.
However you wouldn't know this before buying as Amazon is still using a photo that doesn't actually match the product they are selling.
Cheap(ish) for a reason......Avoid!