All inclusive: eat and drink, all is paid?

Who does not love "freebie"? Perhaps, therefore we like to have a holiday with an all inclusive system. Having paid the cost of stay in a hotel with all conveniences you can spend a week or two without spending any dollar over the paid at home. This generates feeling of total “free-of-charge”. Is it all so simple and easy? Probably not, all inclusive appears to be diversified, and before dreaming about carefree holiday it is recommended to find out the details what is this "all" which is "included".