Colour coordinated bowls of impractical fruit, e.g a bowl of 20 limes because they are green. 
Those massive shiny black leather suites that are invariably wayyyy too large for the room.
Pine. Anywhere.
Magnolia. Anywhere.
Country-style kitchens in modern houses.
Painting bathrooms blue just because blue is associated with water.
Painting rooms yellow to 'brighten it up' no it doesn't fucking brighten it up, it gives me a bloody migrane and looks shit
Those house & home mags when there is a random frilly dress on a hanger outside the wardrobe. WHYYYYYYYY.
Photos in a frame without a mount.
Photos on the wall that are hung too high.
Canvases of really bad pictures.
Canvases bought in hardware shops that have a drawing of a kitchen item on them, like a coffee pot or piles of apples.
Jees, I actually have to stop myself here, else I'd be here forever.