Try Shout. Works for me. I see others use Dawn. I am going to try that as well; stands to reason that it might dissolve grease as that is what it is formulated for.
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Is it an oil or food stain? Usually, I dampen the spot and apply Dawn or another NON-bleaching dish soap. Work into the stain gently and allow to soak for about 10 minutes, then wash as you normally would.
Most dish washing liquids will make gobs of suds so be prepared to rinse and rinse. Air dry. If this doesn't work, there are products like Shout with which I have had good luck. It may take a couple of tries to completely remove the stain.