How do you deal with difficult customers?

Hi everybody, here's a question of a more philosophical nature rather than technical. For all you owner operators who do little jobs for people around the way, what do you do for people who want you to do things that are dangerous or abusive for the machine, or want a big expensive job done way faster and cheaper than is possible.

The first situation I generally attribute to over hopeful ignorance about what these things can do and how expensive it is to fix them.

The second situation,...

How do you deal with difficult customers?

How do you deal with difficult customers?