1950s horror filmmakers were in a quandary. It was a niche market, so they couldn't raise the budget for serious costumes for their monsters. But cheesy costumes didn't horrify audiences, they made them laugh. What to do?
Simple. Be artistic. Show shadows and dub in footsteps and foreboding music. Show the actors reacting to the sight of the monster. Don't try to scare people if you don't have anything to scare them with, just let them know they're supposed to be scared, and they'll oblige.