Sweet dishes taste better at low temperature and salty dishes taste better at high temperature

It is true.

Explanation:

Our taste buds are becoming more sensitive when the temperature of food or drink is lower. This way our brain receives sends us a signal that the taste is stronger.

Sugar, also other sweet things stimulate our taste buds. These receptors are connected with taste buds with the bland connection. These connections are weaker as the temperature is high so the sweet taste is stronger when something is cold. The best example is ice cream.