Lollipops are bad for your teeth because they contain high amounts of sugar. When you consume sugary foods, the bacteria in your mouth feed on the sugar and produce acids that can attack the enamel, leading to tooth decay. Additionally, lollipops are sticky and stay in your mouth for a longer time, increasing the exposure of your teeth to sugar and acidity. Therefore, frequent consumption of lollipops can contribute to dental problems and is not beneficial for dental health.