These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Covered Up: Bobby Darin's rendition of "Mack the Knife".
Draco in Leather Pants: Macheath is the one character most audiences seem to like best, even though he is intended as a despicable villain.
Though of course most productions water down the violence and nastiness of the original a lot, if portrayed the way Brecht wrote him - an amoral pimp, human trafficker and child murderer - this trope is less in play.
Older Than They Think: Several of Macheath's songs are taken from the French renaissance poet (and professional criminal) Francois Villon. It works in the other direction, too: A lot of people are more likely to connect the "Moritat" with Bobby Darrin or Louis Armstrong than Bertolt Brecht.