Why the gauzy look for this raytrace?

[GeneDavis]

I used the OOB settings for "Indoor High Quality" and getting this, after an overnight of passes.

 

Why the soft-focus?

 

I am raytracing again, this time unchecking the "use focal blur" box in the advanced panel.  Early results are better.

 

But why would the OOB settings have that blur?  And what use could the blur have?  Does fuzziness have a place in architectural rendering?

[Flymase]

From looking at the pic it looks like a depth of field blur. You can either uncheck it as you did or use a higher f-stop like f/8 or f/16. The focal blur allows you to focus in on a subject and blur out what you don't want in focus, like a busy background. The higher the f-stop the clearer the pic, the lower the f-stop the blurrier the background/foreground