I mostly watch anime these days so I'm reading subtitles regardless. The dialogue sounds pretty clear, though; I may not know what the words mean but I can easily make out the syllables being spoken. American stuff, though... If it was made in the past 15 years then it's probably going to be full of mumbling and too-loud background noise. I suppose it's possible that my friends have cheap speakers, but I remember sometimes having the same issue at the theater, back when I still went out to see movies.

More recently, I've been watching old British and American shows that a friend has been streaming. Stuff from the 60's and 90's. Didn't have any issues understanding what was said.