The second two were more interesting. They both said that they wanted $125 or $150 to show up at the door and that maybe they could do the job for $150. My response was that I would pay $150 cash when the sink worked, Both had some lame lament about them coming all that way (20 miles) and not getting anything for it. I said that life's a gamble and since I was paying $150 for maybe an hour's work that I should expect a firm commitment to a positive outcome for my money. They then became uninterested in the job. In other words, they were looking for a sure-thing payday whether or not they got the drain cleared!
I spent 20 years working as an electrician. I never charged a client anything if I could not perform the work they required - ever. I think it is an unethical act to show up, get money, drag out your tools and fritter around a bit and then say "jeez, I'm sorry but it'll cost twice what you payed to actually fix the problem," or give some other lame excuse for not doing what you were paid for. Charging for a service call without satisfactorily completing the service is just plain wrong. Anyone got a plumbing snake and want to make $150?