In my red state, I see quite a few Bernie signs and tons of bumper stickers and no Hillary signs and a few bumper stickers. And tons of Trump signs/bumper stickers.
In general, I've observed that Hillary supporters aren't excited about her - they see her as inevitable. (I'm sure there are exceptions who are very excited about her, I just don't encounter them.) But signage doesn't give an indication of how many people are out there that feel that way. Supporting someone you feel is inevitable is not really something that inspires you to put up a sign. Bernie supporters on the other hand, are fired up and realize they have a huge climb. They want to get the message out - so signs make sense.
There's definitely an enthusiasm gap between the candidates. Unfortunately, it seems most voters are willing to just go with the flow and take whoever the media and the "powers-that-be" deem appropriate.