Is there a way to sample the sound of each scale?

Yes - simply swipe from left to right to hear the ascending version of the scale. Swipe from right to left to hear the descending version. 

In addition to showing the notes within one octave of the scale, all notes in that key are displayed for reference in each fingerboard position. Note: During playback, all notes in the key will playback, not just the one octave scale.  

You can adjust the playback speed in the Playback section of the settings menu.