Just a few days ago my brother married and decided to travel to Italy for a long week-end with his wonderful wife. They kept the marriage as an event for the family as it was the legal one. We all gathered in the office of the marriage officer where the wedding was held and went on with a nice long breakfast in a beautiful location. After this good start into the day, my husband and I brought the two of them to the airport from where their honeymoon would start. Everything went easily; they quickly checked in, started off to the security check and looked forward to be just the two of them – it was the first time she left her daughters alone for a few days. Who wouldn't expect them to look forward to nice quiet days?
Upon arrival at the airport in Milan they immediately continued to the car rental service and were looking forward to the little car they had booked in order to continue their journey. After presenting all the papers the car rental officer started preparing the hand-over and asked for their credit card.
This was the moment were the big question mark appeared, neither one of them had a credit card at hand! They started negotiating, they called to have valid credit card data but nothing helped. They wouldn't be handed over a car as long as they didn't have any credit card in their own hand which could be used in the credit card machine in the car rental office expected to hand over the car.
Sure, in the contract details for the car this information had been presented but as they didn't order the car themselves and relied on the person selling them the complete travel. As until then they never had needed to rely on the presence of a credit card they didn't think about it when booking their honeymoon. The travel agent himself, being used to the regular requests for credit cards when checking in in hotels or booking services took the presence of a credit card on a travel for granted and never realized that this might not be true for everyone.
Sure my brother and his wife learned a great deal about communication and traveling, found a solution to arrive at their final destination, and certainly had a memorable experience, nevertheless they'll probably have a grudge towards the travel agency for under-performing. They had expected the travel agent to verify and inform them of all the details needed for a perfect travel.
Small details sometimes become huge mountains if there is a misunderstanding or if an assumption made in the communication proves to be wrong.
Instead of assuming that something has been understood don’t hesitate to verify if it this is really the case. Never forget to make sure that all details which can develop to “single points of failure” are clear to everyone.
In short: If you don't ask the question needed to achieve the expected result you will be seen as a stupid person, the question itself will never be interpreted as being stupid.