How To Avoid Bad Clients from oDesk:

Always Bad clients can hit your freelance reputation hard. Good clients will think of you as a joke, bad clients will think of you as a profit. So if you are in a bad client situation fire them immediately. Look for a more reputable project fitted for your rate and skill. Look for a kind of people to work with that understands you more.
Here are some tips to avoied bad clients away:
   1.Watch the job descriptions and client profiles. Here are additional details to look out for:
Job description: This must be as clear as possible and not "I need a blogger" or I need someone to write an article for me. It's too short to be trusted.

Confirmed to Pay: Freelance marketplace like oDesk, and Elance have indicators that tell whether they verified for payment or not. Do not take your chances by asking for projects on unverified payment.
Bid Price: The bid price must be reasonable enough. Do not work with people offering cents.Never Work For Peanuts
   2.Do not lower your bid rate.Calculate your time and effort for a project before agreeing on the contract. Do not beat the competition by lowering your rate. It will affect your freelancing reputation.
   3.When submitting work samples, submit your portfolio or a link of your own work. Do not submit bare samples or samples that can be stolen from you. Do not do spece work. Requesting for a 500 word article during the application process is an example of spec work
   4.Different contract for different jobs: When your client asks you to do another task not related to what was in the contract, ask for a separate contract and rate, if he declines, withdraw your contract.
   5.Communicate: Communicate with them often so that you both understand what the project is about. Keep him informed every week of your plans and aims for the next week. Keep the conversation simple, not too formal and not too unformal either.
   6.To avoid non-payment, do not accept projects on untrusted websites. To avoid delayed payments, remind them about the payment days before your payment date.

 Remember you Can Fire Your Client Bad clients are pests in your career. Don't waste your time in these types because they are the ones that only gains the benefit not you. You, on the other hand, will loose reputation thereby slowly degrading your business.