Interesting question Shaneaust.
As Asimov has indicated, dew is no big deal on the tube itself. Eyepieces, maps, finders and even slow moving astronomers ..... well dew can be a problem with these though
. Seriously though, I suspect the answer depends on the material your telescope tube is made of.
Another IIS member "bird" has done some research on aluminium vs steel telescope tubes. I understand from his comments, steel tubes have the potential to "super cool" below ambient and cause image degradation due to tube currents. I have seen references to lining the inside of steel dob tubes with a thin layer of cork to resolve this issue. I recently refurbished a small steel tubed dob for our local astro society. As part of this refubishment I covered the outside of the tube with cloth coated with estapol. Apart from the asthetics, I am hoping this will slightly insulate the tube and assist with preventing cold air pooling in the bottom of the tube (the tube is sealed at the bottom - not a good design feature).
What sort of dob do you have?
Regards,