It can be technique, or the guitar, or both. I have an American Fender Strat... so a higher end guitar... it sounds fairly noisy if you were to just listen to me play without amplification. However, plugged in it sounds great and the buzzes & rattles are just part of the tone of the guitar.

Fret buzz that just kills the note, and is heard clearly when the guitar is plugged in is a problem you'll want to address if possible. It can be the way the guitar is setup. Correctly setting up the action and intonation may cure or help the guitar sound a lot better. It may also be that the frets are uneven, and to fix that, you'd need to send the guitar in for an over-haul that might cost more than the guitar did. Some really cheap guitars can also be difficult to setup correctly as the components are such a poor quality its just not possible to dial the guitar in.

If you can hear the buzzes and rattles through your amp, then maybe consider saving up for a better guitar. If you don't hear it through the amp, then I wouldn't worry about if for now. You might also try to find an accomplished guitar player to try your guitar out for you and give you an opinion of how it plays.