If you have an idea for a product, then the ONLY way of knowing whether it'll be successful or not is by doing market research. Many people believe that their product idea is great and that everyone would buy it, but the truth is, you're just guessing. Guessing is not an intelligent way to start a business.
It's always best to do market research and identify first and foremost what people are currently buying on Amazon. Identify a market and what is in high demand. You also need to research the competition and make sure the market isn't too competitive. By spending the time to do proper market research, you can ensure that your product will be successful on Amazon and be able to get in front of potential customers.