We have had some recent discussions about dust on the camera lens and/or
on the digital sensor. 

Dust on film or on a slide will affect the results from a film scanner, as well. 

One of my nearby camera stores suggested using these products ...

Dust-Pro 2000 [UPC 17506-21606]
http://www.pecaproducts.com/cannedair.htm

PEC-12 Archival Photographic Emulsion Cleaner
[UPC 95122-01011]
http://www.adorama.com/CHPEC12.html

and
PEC*Pad Non-abrasive Wipes
[UPC 95122-05011]
http://www.adorama.com/CHPECPP.html

I'm sure that other similar procucts are available -- does anyone have any
additional suggestions? 

--
Martin