Avoid as much as possible.

Asked the attendant to help put in air in my tires, then after a bit of service, was suddenly told about a (gaping) hole that needed repair.

Surprised about it as I was driving for awhile and didn't feel anything.

Went to the vulcanizing shop nearby and then felt the flat tire. How suspicious that now I felt it just after moving a few tens of meters.

When I saw where and the type of hole (clean, slash-like line at the tire sidewall) then the confirmation sunk in that I've just been had by the guys at the station. People at the vulcanizing shop were also acting a lil too friendly than usual, too.

How sad it is that now one even cannot trust franchise stations to be free from sick, brazen stunts like these.

Learning lesson for me. Wanna warn you guys from falling victim to the MO.