Los que escuchan nunca oyen bien de su cuenta

The phrase "Eavesdroppers will never hear any good of themselves" basically means that people who eavesdrop, or people who listen in on conversations, will only hear people saying bad things about them behind their back or without them knowing.

First of all, the type of people that are "listeners" are not the type of people that are thought highly of. Therefore, they don't hear many good things about themselves. Also, when you are desperately looking for something, you don't usually find it. You need to let it find you. Basically, eavesdroppers don't hear compliments being thrown around about themselves because they are so wound up in their own little game that they become antisocial and disliked.

Everything Your Listeners Ever Wanted to Hear by Rush... But You Were Afraid to Play was created in 1977-01.