Well with all the wheel bearing failure threads I am really surprised there have not been more muffler bearings fail!
I was in the bearing and industrial power transmission industry for 40'years. The first joke ever played on me in my early days was for people to call me and ask if I sold "Muffler Bearings"!
Muffler bearings only go bad if the muffler belt isn't correctly aligned or has the incorrect tension.
Much worse is letting your blinker fluid cylinder go dry.
I just finished prepping my bike for a 2-1/2 week tour that I'm starting on Wednesday. My muffler bearings were fine. I switched all my blinkers out to LEDs so I don't need blinker fluid anymore.