Alex
Steve's picture using the masking tape is the way to go. It isn't unknown for a commercial prospect to ask you to demo "the area around the coffee machine" when in reality that's all they want cleaning, and they've just had it done for nowt
If you're demoing stain removal, put the tape through the stain, so it's not all treated. You need to show the benefits of your service, but they must still retain the need to have the work done. Having said all of the above, there will also be occasions where you deem it necessary to clean a whole area and feather it in, so you'll need to make a judgement on each occasion.
As for payment, on completion is always the goal, but not always achieveable. If you still want the work but have to give credit, you may wish to consider working penalties into your costings for late payment, or incentives for early payment. Something like a £100 job: Terms: 30 days net.
For payment received in this office by 19th Nov. 2003 the sum of £10 may be deducted from the above total.
Just another option for you to consider.
