I definitely think shy clinton is far more common than shy trump - for a lot of the same reasons as shy Obama was always more than shy Romney. Demographics are destiny - and Trump sealed his own fate a long time ago - and a lot of voters marked "unlikely" are going to come out in droves to vote for Clinton, especially in the hispanic community. White men think their wives are going to vote for Trump, the reason why they believe there is a shy trump effect, but their wives are really going to vote for Clinton. And of course, there are people at the ballot box, facing their possible decision of voting for Trump, and ending up not going through with it because of WHO HE IS. These are right-leaning independents or even Republicans who are "for" trump but have been fighting with the idea of voting for him because, well, he's Trump.
This isn't about "shy Clinton supporters" (I don't put much stock in the shy voter hypothesis, especially not in the United States) but I think Trump is going to do poorly with current undecideds, unlike what some people were saying on here earlier. No one is on the fence about Trump at this point, you either like him or hate him. I think most the undecideds are people who know they're not going to vote for Trump, and just haven't decided if they're going to vote Clinton, vote third party, or stay home. Any of those choices spells doom for Trump.
