I've had a recording engineer who also makes speakers (I owned one of his TL-D1s) and CDs over to my place several times over the years. First thing he did was walk around, clapping his hands and checking out the corners. I asked him if I needed room treatments and he said "No, your room is fine. There's no echo."
He even pointed up to the popcorn ceiling and smiled. I guess it's better than a smooth flat surface. It's a small room, relatively speaking, but I do sit 9' back from the speakers with the rear wall behind my head.
Before anyone complains about reflections, remember that if the distance from your head to the rear wall is less than the circumference of your head, your ear-brain mechanism will filter out reflections. Ask any spelunker how they locate someone lost in caves. They put their back up against the rocks and listen. Besides, it takes delays of over 40ms to be perceived as an echo and that's not just gonna happen in my room.
I've also had a high end and well respected audio dealer over a few times and he enjoys my listening space. I use no room treatments at all. Sometimes with a near field listening set up you can get really good sound with not much fuss.
Recording studios are there for getting the most out of a recording and once done, there's no great need, if any, to replicate that same environment. The work is done. Sit back and enjoy the sound.
All the best,
Nonoise