My contributors can't see digital items for sale?
That is correct, the store will not try to sell digital items to the owner of the media. No point in trying to sell digital items to someone that already owns that original media that was uploaded. However anyone else (anyone that didn't upload the media being viewed) will see the digital items for sale, only the contributor that uploaded the media will not see it.
But the member has logged out of their account and they still can't see it?
That is correct, a member can log out of their account but the store still knows who that person is so it still will not show them the digital items for sale. Only those that didn't upload that media will see the digital items for sale.
Ok, but as the contribuor myself I wanted to test and see this, is there a way?
Yes there is, but it would require you to log out of your store front as the contributor. Then while on your store front hit ctrl + r (kill all sessions). Then clear your browser cache, and delete cookies. Now the store shouldn't know who you are and will show you the digital items.
It would be easier to just have a second browser that has never logged into that contributors account, and use it as a "visitors point of view" to browse photos on your store front for testing.
But it shows in a different browser?
That is correct it may or may not show in another browser depending on if that browser was ever used to log into that account before. The store knows who the person is based on a cookie, each browser must have it's own cookie.