During the 1930s, Gangster movies you would have characters like James Cagney who was no ones fool rising to the top of his seedy underworld killing anyone who got in his way or who he thought was in his way wearing flashy looking Mens Suits
which usually consisted of a bold striped double breasted suit with wide lapels. Now this type of suit is now called gangster stripe for several reasons. First, most mens suits that are used for business aren't trying to have bold looking stripes on it like gangster stripes but try to have more muted looking stripes or patterns.
You're not supposed to be loud dressing in the business world at all. Second, the lapels were usually wider than your general suit lapels, which immediately tell a person that you were what you like and you're not another empty suit in an office somewhere toeing the company line. The pants on a double breasted style suit that James Cagney wore would also have baggy pleated pants while business suits were regular cut and flat front without pleats. Wearing spectator shoes was also something you would never see in an office anywhere but you would see a gangster in the movies wearing those fancy looking black and white dress shoes not giving a hoot if he stood out from the crowd because that is what he wanted to do.