I do the frames, when & if, in my opinion they need to be freshened up, I don't charge extra for this as it takes literally minutes to do the lot, and I dont even point it out to the customer,unless there was a load of bird poo on them.
However it seems a bit rich for trad cleaners to make these observations about WFP Users , when its clear that not all of them clean the whole frame each time {why should they} I say this because I have allways been puzzled how the Trad guys get away with leaving windows above conservatories uncleaned because they can't get to them. So they clean only 3/4 of the windows in some houses.