i also refuse certain conny roofs(flat ones with hardly any fall on them usually)as their a pain to clean,i also wont take on any window cleaning work that involves climbing over a flat roof to access the backs.
gutter clearing is another job that i dont do any more(unless access is easy and its part of a well priced full house valet)
i wouldnt clean a mid terraced house either unless i could clean the whole row,etc,etc
i dont need to as im busy enough cleaning all my regular (easier) work.im also 45 years of age and dont want to be fannying around with PITA jobs.
at one time id clean anything and ive learned through experience what jobs i will and wont do.
besides i want to keep my working hours down so i can enjoy my leisure time too.(6 or 7 hours a day is enough for me these days)