[synu]

It was the middle part between the two bits you quoted - he was just going to a show, was in a phase where he liked wearing all black, and would get waved in without even intentionally trying to trick anyone because they assumed he was arriving for work. Does that help?

[yunohn]

I didn’t interpret “show up” as having purchased tickets and planned to enter, rather unintentionally get let in as was their implication.

[synu]

Show up can just mean arrive, no implication one way or the other.

[bigiain]

Yeah. These would all have been "show up and pay at the door" type places, not sold out weeks in advance with pre-booked tickets. Bouncer (or sometimes door bitch) takes your money, unless the bouncer waves you through.