  The recent detection of gravitational waves has generated interest in
alternatives to the black hole interpretation of sources. One set of such
alternatives involves a prediction of gravitational wave "echoes". We consider
two aspects of possible echoes: First, general features of echoes coming from
spacetime reflecting conditions. We find that the detailed nature of such
echoes does not bear any clear relationship to quasi-normal frequencies.
Second, we point out the pitfalls in the analysis of local reflecting "walls"
near the horizon of rapidly rotating black holes.
