Too much furniture or large stuff or outdated styles, colors and patterns can make the room look packed as well as unattractive. It will defeat the entire staging purpose. Professionals will make the rooms look spacious and very appealing making buyers imagine living and enjoying the space.
Art hung very high or can be very small or not blend with room theme can make it look out of place. The art needs to exaggerate and improve room appearance.
Using small or outdated items or wrong size or too much color or too many items used to accessorize the place can make the room appear messy and imbalanced to onlookers. On the other hand, too much white without any contrast will look uninteresting to buyers.