After 90 days, Costco will not take back electronics, including TVs, large appliances, computers, tablets, cellphones, smartwatches, and cameras. That's still a pretty good deal if you're trying to assess what size screen to get, or what sound system works best in your home.
Although some states allow returns of alcohol and tobacco products, in most places it's illegal for stores to accept returns of these items. Costco recommends checking with your local warehouse club before attempting to return wine, beer, or spirits.
Costco's return policy has additional exceptions for products with a limited useful life expectancy, such as tires and batteries, and for special-order and custom-installed purchases. Amid the hoarding sprees early in the pandemic, the warehouse club temporarily stopped accepting returns of toilet paper, paper towels, rice, bottled water, sanitizing wipes, Lysol, and soap.