I never understand this possition. If you'd emotionally benefit from a holiday or anything else and you don't have the immediate cash, but the interest payable is relatively nominal - go for it.
I've just put something on card that I'd have the cash for in a month but will probably prefer to pay it off over ~3 months to retain a cash blanket for other things. The interest will only be ~£30 which is a nominal sum to me. That said, I'm otherwise financially secure.
Paying interest does not necessarily equal financial mismanagement.
@SideWinder - work out the interest and see if it's nominal or not to you.