Most freelancers have already encountered clients which would do and say anything just to get the most out of their hired freelancer or part-timer. Some clients exploit the negotiating process and low-ball the rate of the project while other’s milk their service providers with every cent that their paying them, making revisions after revisions and minor adjustments that take forever.
These “clients-from hell” often promise more work in the future if you’ll give the “present” work at a discounted rate. Saying that they need to “test” you out first before they pass on projects at a regular basis. When you get this type of client, watch out. The pay you’ll be receiving (if it’s enough, that is) is not worth the headache and stress that you’ll get.
In case the inevitable happens and you got cornered and said yes to a project, try finishing it as quickly as possible (with quality of course). After that, learn to say NO once they seek your services again. You are better spending your time on other valuable and less-stressful projects with not-so-picky clients.
Some things are just not worth it.