I almost always have a fight with hotel showers. I feel like I'm on The Crystal Maze with most of them, trying to turn them on. It's always pull this knob while turning this dial and pressing the button to your left simultaneously. I just returned from a lovely BnB which had a shower only, no bath and all you had to do was press a button. It was great.
Hoover cords are another nemesis of mine. It doesn't matter what I do, they always end up tangled and kinked. I really need to get another cordless vacuum.
What inanimate objects are your nemesis?