I like a home to be comfortable, cosy and personal, so my nemesis decor features include:
Oversized sofas. They can often dominate a room, and inevitably end up triggering an uncomfortable case of dangly leg syndrome where my ankles are forced to stick out parallel to the floor 6 inches from the edge of the seat.
A related offender is those ruddy sofas with a back composed of oversized cushions that exist only to swallow you up.
Excessive use of neutrals/ grey/ magnolia. Can easily look bland, cold and impersonal.
Rooms that look like they've come out of a catalogue. IKEA has a branch nearby so there's lots of replica IKEA show home looks. We've got several pieces as we're struggling to replace with equally practical, long term furniture, but its when all the furniture, pictures and trimmings have the look too.
Hard floor surfaces in rooms for relaxing. Unfortunately we bought our house off a laminate fiend. The one in our bedroom is reasonable quality and low on the list of intolerable crimes for replacement, but it's joyless having a hard floor and I hate chasing dustballs when trying to clean it.
The shitty shiny cheap laminate in the lounge was gleefully ripped out in less than six months. The first priority however was to fill in the evil spotlights that glared off the shitty shiny cheap laminate casting intense pools of light and dark triggering headaches.
The lounge was pretty much the antithesis of our taste. As well as the crap floor and lights, it had a 1970s inspired brown feature wall of bold wallpaper, and nearly co-ordinating brown wallpaper* in a shade best described as "watery value hot chocolate". This was highly unlikely to be original 1970s original decor as the house was built in the late 80s 
The next crime to be inflicted on the room was the poky undersized hole-in-the-wall fireplace with a greedy gas fire that sent the heat up the chimney by-passing the room completely. I chose the house for its potential 
The daido rail in the hall should probably count, but I quite like it. It breaks the space up, and means that the bottom half doesn't have to be a battered marked light colour.
Being an 80s house, the artex ceilings count as an original feature and are too awkward to replace. Sigh.
Hard floor tiles worry me about breakages. I like vinyl in a kitchen. Warm and a fair chance of the crockery bouncing.
Photos are good except the mock-casual heavily posed "aren't we having such jolly fun" type on the bland white background. Give me a stuffy formal pose any day, at least it's honest.
Did any one mention words/ mottos being used as art?
- Some feature walls can be nice. I like colour and done well they can be a good way of using strong colours. This brown combo did look like the aftermath of a mud bath though.