Stayed 3 nights with DH's friends. They stay with us from time to time. (FYI we have a family bathroom with walk-in shower plus an extra bathroom downstairs with bath only, our guests welcome to use both). They had a new house, gave us the guided tour. Lovely guestroom with a guest bathroom next to it but guest bathroom only had a bath with a shower-attachment (think 3/4 tiled bath with a low-level shower attachment designed for hair-washing). Their en-suite had a walk-in power shower.
So first morning, after breakfast I asked hostess can I use your walk-in shower, she looked surprised but said ok. So I had a quick 10-min shower. When I came out her DP was in bedroom doing up his shirt, he looked at me in shock, said 'guest bathroom's down the hall' so I explained his wife had said i can use en-suite as I wanted a proper shower. Later my DH said his friend had asked him to tell me not to use their en-suite next time! 
So for rest of visit I had to crouch in bath-tub washing myself with a handheld shower attachment! DH shrugged it off but i think it's very rude not to let guests use the only decent shower! Was IBU to think they should have let us use their en-suite?