A number of people have an issue with keeping the grates and burners of a stove clean. They are just one of those places that tends to get more dirt than most in the kitchen. You have the suggestion you clean them or wipe them daily. But you can also try to wipe them with a damp sponge. If that doesn't work I've tried the baking soda and vinegar that seemed to get the grimy parts and burned on parts with little to no scrubbing. The grates they say you can remove and add them to a sink full of hot soapy water, for 30 minutes. Then adding a teaspoon of ammonia to the sink water to help loosen the grime. You can either grab a stiff brush or a scrubby pad to remove any other spots that need a little extra time to remove the grime.