Cloudiness seems to be common in these Sharp Full Array LED sets. I've had two 732's (warranty replacement) and both show cloudiness to varying degrees. The first was bad enough to get a replacement. The on the second set I can only see the cloudiness under conditions designed to bring it out.
I suggest using a lowest back light level you can -- the brighter the overall picture the more visible the clouds can be. Particularly at night.
If your set is bad enough that you can see the clouds during normal viewing (in non-black areas of the screen), Sharp might replace the set.
Here's a before and after on my set.