What can you not return to Costco?

Excuse me, I'm a bit confused about Costco's return policy. Could you please clarify what items are not eligible for return? I've heard that some electronics and perishable goods might be excluded, but I'm not sure about the specifics. Are there any other categories of products that I should be aware of before making a purchase? It would be really helpful if you could provide me with a comprehensive list of items that cannot be returned to Costco.