Unplug your toaster and allow the appliance to cool completely before cleaning it. Once cool, remove the crumb tray from the bottom (if the toaster has one) over the sink or trashcan to reduce the number of crumbs on the countertop. Gently brush the crumbs into the sink or can, then clean the tray in soapy water and rinse. Allow the tray to dry completely before re-inserting it into the toaster. If the tray can’t be removed, shake the cool, unplugged toaster upside down over the sink or trash can.
Apply glass cleaner to a cloth to clean the outside of a chrome toaster; substitute an all-purpose household cleaner (or highly diluted hand dishwashing liquid) on plastic or enameled metal toaster shells. Wipe well with clean water to rinse, then dry.
Toasters have a habit of attracting hard-to-remove spots that get baked on by high heat. Soak a paper towel in all-purpose cleaner and place it over baked-on spots for several minutes, making sure the toaster is cool and unplugged before starting. The cleaner will help dissolve the stain over time. Follow up by cleaning the rest of the shell as usual.
Don’t use abrasive pads or cleansers on the outside of any toaster, because it’s easy to scratch these surfaces permanently. Never stick any tool inside a toaster, which can damage the heating elements. Never spray, or pour liquid on or into, any electrical device — always apply cleaner to the cloth, never the appliance.
References:
Don Aslett, The Cleaning Encyclopedia: Your A to Z Illustrated Guide to Cleaning Like the Pros.
Jeff Bredenberg, editor, Clean It Fast, Clean It Right: The Ultimate Guide to Making Everything You Own Sparkle & Shine.