I always wondered why, if the Earth were so damned bright on certain radio frequencies, why we didn't listen to those frequencies when searching for ET. Eventually I found out it was because the telescopes of the time couldn't tell terrestrial signals from extra-terrestrial ones. Now that appears to have changed.

I wonder if an alien species would be embarrassed that the first we found out about it was by picking up its re-runs of I Love LU-324'ingy?