Is cheap away arduino trustworthy
Caveat Emptor.

If it's not genuine you can never be sure quite what you are getting. You have to ask with some of then just how they can make them so cheap. Poor quality components is one way. Either counterfeit or reject components which may fail after a short time, or under certain conditions is a big risk.

There are different grades of board each with their own risks...


Genuine. High price, good reliability and quality. Good after sales support. Supports the Arduino cause.
Arduino clone. Genuine Arduino design made by a reputable third party. Almost as good as option 1 but doesn't support Arduino financially.
Arduino Based. A board created for a specific job that is based around genuine Arduino design. Support really only from the (often smaller) manufacturer. Quality varies.
Chinese clone. Low grade components made to original Arduino designs. Little or no support. Poor quality. Often with different USB interface that is unstable and low quality.
Counterfeit. Low quality components. Claims to be a genuine Arduino. Bad build quality.


Options 1-3 are ones I would consider buying. 4 and 5 I would stay well away from.