I can't get my head around 4K TV's specially when I am watching a film. The films look like they have been filmed using the same process as cheap American TV series, watched back to the future part 2 on one yesterday and it killed a classic film for me.
Caveat I am a bit of a FOC.
That an actual thing. It's called the soap opera effect and it's to do with motion bluring or motion smoothing the n the tv and it can be a pain in the arse.
In simple terms new 4k TVs the panels are designed to broadcast in at least 60 frames a second. Now this is great if your playing video games or if your watching sports as the motion blur with emliintnate the ghost trail of a ball if your watching football or cricket say and it makes video games display smoother.
However it's not good for watching films or TV shows. You seen films and TV shows are produced at 24 frames per second. This means the TV is adding an extra 36 "fake" frames per second to make the picture smoother which gives an almost waxy or fake look.
Now there's a couple of ways this can be corrected. First go into your picture settings and turn off motion blurring or smoothing and also turn the colour down as it'll be really high.
All TVs come with preset picture modes and yours will probably be on dynamic or natural mode. DONT USE THEM!! switch it to standard or movie mode and they won't have motion bluring/smoothing. You'll still have to adjust the colour or contrast though to tour liking.
If you have a new Samsung or LG it will have another mode called filmmaker mode. This mode has been developed by all the major film studios as there were a lot of complaints from customers about this soap opera effect. Is you have this the picture settings will be perfect for watching films and TV shows as all the motion blur settings are turned off and the contrast and colour setting are perfect for films/TV.
I have filmmaker mode on my TV and it's brilliant. I don't use anything else apart from game mode when I'm on my Xbox.
There's hundreds of guides for great picture settings and the soap opera effect online. Just type your make and model number best picture settings and you'll get a better picture with half an hour!