I should have mentioned: My dustiest lens is a Nikkor 105mm f/4 macro. If you looked into this lens you'd wonder how it ever took a good picture...but it's by far the sharpest, most contrasty lens I own for my Nikon. A macro lens used in macro mode would be the first place I'd expect to see the effects of dust...and I see absolutely nothing with this lens. I'll bet your 55mm is just as good.

Be well.