“So you’re wondering why there are so many snakes onstage, right?” Taylor Swift asked the crowd on the opening night of her “Reptiles” — sorry, “Reputation” tour. It’d crossed the collective mind of the capacity crowd of 59,000 inside University of Phoenix Stadium in Glendale, Ariz. on May 8. The golden snake microphone might have required a bit of squinting to make out, but it was a fairly in-your-face move to position three enormous inflatable snakes around the stadium, hovering over the two rear stages as well as the main one. It’s not like anybody needsa good reason to float over a football field’s worth of fans in a snake-shaped cage, but Swift intended to explain how pop’s most celebrated cat lady had come to claim cobras as her new spirit animal.

“Someone called me a snake on social media, and it caught on,” Swift said, not even...