I grill a lot of burgers and steaks and never put any sauces on them, yet my grill gets crudded up also. Fat can do it just as well as sugar. And my grills are stainless steel, not nearly as difficult to clean as cast iron.

There's no magic for removing the crud. If you use chemicals like oven cleaners or other solutions, you are definitely risking the longevity of the grill. There's no substitute for a little elbow grease, but there are some things that will make the chore easier. 1) Work with the grill when hot. Because after grilling you're more interested in eating than cleaning, lots of folks, maybe most, wait till the next time and clean the grill while really hot, before they put food on. Trying to clean it while cold is difficult, maybe even pointless. 2) Use the right tool. I use a wad of tin foil held in a pair of really long tongs. Some of the wire brushes can damage the grill. I have a really good brass bristle grill brush, but I hate to clean it. Foil is just as good, and easy to toss when done. 3) After cleaning and before putting food on, use a wad of paper towels with some cooking oil on them to lubricate the grill. This will prevent a lot of the buildup of crud next time.