I think the pitfall is getting too cute with patterns, or too much pure modernism (space age/corporate office, overly sleek furniture).

You want industrial not modern touches in the furniture (ex. unfinished wood rather than super shiny lacquered wood) and one patterned rug or one patterned accent wall or flooring is usually the limit for mcm. No pattern mixing unless they’re just accent pillows or vases or little items like that.

Also mixing too many disparate colors in your decor. Avoid combinations like mustard yellow, lime green and orange, etc.

Combine those three tendencies and you end up with aesthetics straight out of the 70’s.

As Candy Lawn said, “understated” is very integral to well delivered MCM style.