Maybe but You would have to narrow it down more,
first clean customer pays cleaner £20 for a first clean you get £20, 2nd clean customer pays cleaner £20 for 2nd clean you get £20 3rd clean customer cancels you are out with 200% , cleaner has made 2x running costs losses and worked for nothing what would you do in these situations?
10 of these and your cleaner may/will get anoyed,and start cherry picking your work to the point that he is almost aggressive telling customers its minium 6 cleans please let me know before i clean , then you get pop central of 50% before the first clean.
you gota work out a rate/deal that aint to much to window cleaner and a rate that keeps u in work all year round u prob will get a few customers charging 200% over 2 cleans but i dont think people will be biting as hard if it was cheaper.
end of the day a window cleaner could simply employ his own canvasser and give him say £3 per lead any decent doorknocker should pull 4 leads an hour, half of these will be jobs it works out alot cheaper then 200% the cleaner might get a plooder who doesnt do his reknocks or make knock sheets so work will be all over the place rather then more compact but still. alot cheaper and its all a numbers game
so the trick is you offer a more professional approach naturally for more then a random but why would a cleaner employ his own if you can offer him a decent deal is 200% a decent offer? that you would have to confirm with others people who are desperate will take you on but would they use you again and again i dont know,
i guess if someone is prepaid to give you 100% 2 times and understand he may have 45% left by the time you are out then fine
you defo are being more open minded, i think you aint far from it , rather then taking money upfront then refunding you are only charing for what comes on i still think thou with running costs 200% a bit to much for all year round work however you will have the edge over many and someone will give you a try!