Nevada's polling oddities, including overestimating GOP support and a "newspaper's" horrible record with surveys, is explored in a post for Latino Decisions by UNLV Professor David Damore.
Damore found that polling here, as I have pointed out, has underestimated Democratic strength in surveys for the last three cycles, and he singles out Mason-Dixon, once used by the Las Vegas Review-Journal, and Survey USA, now used by the "newspaper," as prime evidence of the phenomenon. Damore also explored the difficulty that pollsters have had gauging the Latino vote here, which clearly has helped exacerbate the GOP bias in many polls.
Damore's key findings:
Here's his full post.