I only saw Burns & Bono a couple of times.  They were fabulous.   When Mary sang, she rocked the whole place.  She could sound like anybody that she wanted to, and even did some acts better than the real performers did them themselves.  I considered her the "real" star of the show.  I had heard that she and Russ were brother & sister, but never got that confirmed for sure.

One night in particular, I remember that my boyfriend (at the time) and I went there to see them, him for the first time, myself for probably the second or third time.  Mary started singing an Elvis song.  She sounded exactly like him.  My boyfriend said "that is not her; she is lip-synching to an Elvis record".  I told him, no, it definitely was her voice.  Then, (this is the funny part).  She stopped at a table right next to ours, and continued singing her Elvis song directly to this girl who didn't look the least bit interested.  Mary stopped in mid-song, and said, with her hand-held microphone and her signature booming voice:  "What's the matter, BITCH, don't you like the King?"   Needless to say, the place went wild.  That's when my boyfriend was convinced that it was really her singing!