The effect of sensor dust/dirt at small f/stop numbers (i.e. reasonable apertures)

[FocusTester]

On lenses that I have which allow me to stop down to f/32 or even f/45 on my full-frame SLR (Canon 6d), I can often see sensor dust, especially in uniformly lit relatively bright low contrast areas. I guess this is an inevitable side effect of changing lenses often and allowing dust to get into the camera. However, as I change the aperture setting of my shots to more "reasonable" lower f/stop numbers, the dust seems to just fade away as I go wider than around f/16. My question is:

How do the dust and other particles on the sensor (or sensor's filter to be more precise) affect images at more wide open apertures? After all, the dust/dirt is still there. It certainly becomes more difficult to make out at the pixel-peeper level, losing contrast as one opens to apertures wider than f/16. Still, it must have some affect on the images. What effect does it have?

 

[amolitor]

That is normal, and is essentially the same effect as DoF. The dust is "out of focus" wider open.

It's not quite the same as in/out of focus and depth of field since it's on the other side of the lens, but it's a very closely related effect and works in much the same way.

 

[FocusTester]

That is normal, and is essentially the same effect as DoF. The dust is "out of focus" wider open.

I guess I am trying to figure out how it effects the image in the vicinity of the out of focus dust. That is, are the pixels in the vicinity just darker, less contrasty, or what?