Given how broad a reach the Marvel Cinematic Universe actually has, it would be almost impossible for it to please every single person who watches one or all of its movies.
Enormous popularity breeds a massively diverse pool of fans, each with their own values, beliefs and individual ways of looking at movies, meaning that the person sat next to you could view a certain character, plot point or line of dialogue in a completely different light than you do.
This means that certain parts of the MCU have rubbed some people the wrong way, though that won't have been the aim of the filmmakers. Whether it's a specific scene in a film upsetting fans of the comic-books, or the simple studio politics of the franchise itself, it's been an eventful nine years for Iron Man and friends, and a journey that's packed more than a couple of highly controversial moments.
Whether you agree that the following ten instances warranted any controversy or not is entirely up to you, but it's impossible to deny that they caused a stir, and it's important to appreciate that there are always two sides to every coin.