According to DIN 4844, there are two ways of marking dangerous things in industrial areas: Black and yellow stripes for moving things (like doors or lifts), red and white stripes for immobile things (like stairs or loading ramps you could easily crash into).
But in the meantime, everything is getting black and yellow, no matter if it is moving or not. Or even no matter if it is dangerous or not. It looks so cool so the stripes got to be put on the edges of tables, any lame stair, doors of supermarkets ...
So how can one recognize of something is really dangerous now?