If the generic product image is being used, but the bottle type shown isn't matching (ex: red wine, but the white wine bottle is showing), you can easily fix this by updating the item's Product Type and Category. Once those fields are updated, the correct image will appear
Click on the Products tab (or enter the product code in the search box)
Click on the selected product
Click on Edit Product
Scroll down to Origin
Update Category and Product Type
Click Save
It will take 15 minutes to auto-refresh
To force publish, you can go to My Account >> Manage >> Marketplace Settings >> Publish Updates