Performing in Scotland as part of her "Witness" world tour, the singer checked out a local cinema and was even spotted chatting with fans by the river Clyde.
However, when it came to grabbing a bite to eat she struggled to get anywhere at short notice.
According to The Sun, she told fans during her show that she had been on the internet looking up the "top 25 places for dinner" in the city, stating: "Some are really fancy, some only sit, like, 10 people.
"I called a couple of places and couldn’t get in anywhere."
It seems the star was delighted though to have found an ideal replacement in Taco Bell, which had perhaps surprisingly made its way onto the list, so she added that she ended up going there instead.
We are sure she wasn't too disappointed, as judging by her instagram account, she is already a big fan of the US Tex-Mex chain.
The team at Bilson Eleven in the city's East End did end up disappointed though, as they were one of the venues the singer tried and who were forced to knock the star back.
Owner Liz Rietz told the Sun that she would have loved for Katy and her team to have been able to dine with them but that "24 hours notice for ten people was just not possible" and that as they only sit 20 people they feel they have a duty to "honour the bookings" of their current customers.
Maybe book ahead next time Katy.