I did a search and couldn't find this anywhere so hope it hasn't been covered before.
I am flying Spirit for the first time (not my choice - it's a long story) and am wondering how they know if you have paid for your carryon? Is it on your boarding pass? Is there a sticker or something? Puzzled.
I have no intention of paying for carryon and will fit whatever I need for my 9-day trip under the seat in front of me. This is definitely the airline for the guy with no bags, just a really big overcoat with a lot of pockets!