What do you clean the inside of a refrigerator with?

Use baking soda in warm water. Rinse well with clean rag to remove gritty feel.

You can also use a mixture of vinegar and water, or bleach and water, or ammonia and water. If you use the bleach or ammonia, be sure to wipe down all surfaces with warm soapy water. Or, you could just use the warm soapy water.