Not receiving string messages from SQS
You Can manually check by visiting your aws console, whether your message are in proper format. Verify that.
I am working with SQS. I am sending messages from a java code and receiving it from a python script. I am sending json object in string form using JSONObject.toString(). Sometimes python script receive the proper string but sometimes it get the message in following format:  
���'��eq��z��߭��N��n6�N��~��~��m=���v+���Myӟ=���e�M�ߟv׎�۽y�����8��w��;�M��N�۞�㾹뾷�n���7�}7�o=��4۽����߾v��6��<�}7�}4�ν��=���߾{��}�n6���߭��^������~���|�]��N��~��κ�����y�������^��}��M��θ��:�^�����_|߮6��5�^�q��z�ږǫiخ�����n�Wږǭʗ�9�������F���8�����4�N�u��q�������_o�<���o�Zo�<�n�뗷