well as with anything in life, there will be a small risk of some nefarious little scrote taking the piss, but equally that may not be the case - if you get a gut feeling about the potential viewer/test rider I would say go with your feeling and ask for some form of deposit
as a general rule of thumb if they are wearing sports leisure wear and look like they don't actually take much exercise, proceed with caution
well as with anything in life, there will be a small risk of some nefarious little scrote taking the piss, but equally that may not be the case - if you get a gut feeling about the potential viewer/test rider I would say go with your feeling and ask for some form of deposit
as a general rule of thumb if they are wearing sports leisure wear and look like they don't actually take much exercise, proceed with caution