I've stopped purchasing items sold by 3rd party sellers on Amazon and it becomes a much better site.
Unfortunately it seems you can no longer filter search results by "Sold and Shipped by Amazon", you have to filter by "Available from Amazon Prime/free shipping" and then filter manually which is a pain.
Unfortunately, this is not enough anymore. Amazon commingles their legit inventory with 3rd party inventory that drop ships from their warehouses. They don't differentiate between the two inventories, so you can still end up with a counterfeit product; even when "Sold and Shipped by Amazon".
I've actually had better luck with 3rd Party sellers that ship on their own (not from an Amazon Warehouse). If they send you a counterfeit, their store reputation is going to take a hit. Though at this point, eBay might be a better option.
Lately, I've started buying direct from the manufacturer when possible, or shipped from B&M store. Their prices are the same, or better.
The 3rd party market place on Amazon has become Aliexpress with higher markups. Unless I have an immediate need and I can not find the item locally, I just order it from Ali.
Unfortunately it seems you can no longer filter search results by "Sold and Shipped by Amazon", you have to filter by "Available from Amazon Prime/free shipping" and then filter manually which is a pain.