From what i can gather on this forum there appears to be two school of thoughts on the this subject
it seems to come across as a specialist job,ie dry vacumn cleaning/using the wfp,etc and seems to command a high price or throw the ladders up and a quick £40.00 for a couple of hours,i must admit i seem to be the latter and i tend to clean the inside and outsides with my hand,spray cleaner,cloths rather than use the pole.
if i was cleaning a semi which may only have guttering on the front and back to me £40.00 is good
i would point out in most if not all cases there is two of us doing it,one on the ladder the other footing it if not two of us then i use a bag of sand to weight the ladder
(look out in coming elf and safety missiles)