The correct answer to this open question is the following.
The worst thing that happened to me on a vacation was that the beach resort where we had our reservations was very expensive and the quality of the services, very poor compared to the excessive prices they charged us.
We spent one week of family vacation on that property. We had great expectations of the service, and not only for what we saw on the website but because of the amount of money the resort charged us in advance for the reservation.
We learned that good service is not related to high pricing.
The property was nice, but it was such a pity that the employees were not as high as the standards of service of a place like that.
For instance, we paid 55 dollars brunch per person. We were expecting great international food cooked by world-famous chefs and with superb attention from the waiters and the captain. But those 55 dollars seemed to be too much for such a poor service.
The food was not good. The food was cold.
And something similar regarding poor service happened the seven days we stayed there.
The lesson was that high price has nothing to do with great service. And learned the hard way.