Listening differences between a.e. and b.e.

I have a little difficulty when I hear films in American English, to tell the truth, sometimes I cannot make out some american actors/ actresses for example Humphrey Bogart and Harrison Ford. This also happens to me when I hear some scottish or irish ones. What I mean with all this is that in schools and most courses we only hear perfect dubbings in perfect oxford english while in real life there are a lot of accents. Does it happen to you anything similar?