To verify the quality of your scope you should always do a star test and verify that the scope is at least well collimated. Read your users manual on instructions on how to collimate. There are times during shipping and transport when the optics can get knocked out of alignment. Some scopes (such as ETXs) aren't recommended for self-collimation. The star test also allows you to rate the optics you're using.
Ah yes, that reminds me that there's sometimes other areas which may degrade observing performance like poor star diagonals/prisms, eyepieces, or barlows. Often times mass marketed scopes come with poor quality eyepieces.
Also, it's best to let your scope sit outside for some time so that it equalizes with the ambient temperature. If you don't, you'll get air currents in the tube of the scope which will degrade performance.
Of course, some times its not the scope/optics itself, but either bad seeing conditions (twinkling stars are signs of bad seeing) in which case you simply need to be patient and wait for another night, or over-polluted skies which will reduce contrast. In the later case, you need to find a new site away from urban light polluted areas.Here's a few links: