One of question we get all of the time is: "What shouldn’t go in the dumpster?"
Most basic answer: anything in liquid family or related to it. Cleaning liquids, chemicals, wet paint (completely dried out paint cans are okay), batteries (because of battery acid), oil based materials (ex. tires). Biological hazards/waste are an obvious no-no; as are hazardous materials. Lightbulbs, asbestos and freon-based items (including appliances such as: refrigerators, Air conditioning units, etc.), and electronics (televisions, monitors, printers, etc.) also should not be dumped. Also avoid dumping gas cans, oil cans, and propane tanks.