My most hated one:
"Do you prefer cash or a cheque? I bet you like cash so you don't have to declare it".
Me: Stoney-faced 
lol
its like all the taxi drives, who people try to haggle down on price, saying they can pocket the money and dont have to tell anyone
i dont mind custy not having money to pay, as you can catch up with them, its when they make up bull to try and get out of paying, as they havent got guts to cancel, or they wait for you to do front then say dont do it this month
i dumped one custy half way throught there first clean, windows where green with crap and black in side from dirt, and i knocked on the door for something and took them 5 minutes to answer door, do you know when you get that feeling these are going to be pains and never pay, still do there neighbour house and when i pull up in van they wont come out of house lol i think they think i am going to demand my money