The problem at the moment is that hardline social conservatives are getting all the attention, and the candidates are pandering to them. If all you hear is that lot, it leads you to the conclusion that Republicans as a breed are all bigoted pieces of shit. This clearly isn't the case, but it's all we're hearing at the moment. When you have that moment posted earlier where people dying from lack of healthcare is cheered, or when the huge amount of executions in Texas is cheered, or when a US soldier currently serving is booed purely because he's gay - you form opinions of the whole group, fast.
That's not to say the general Republican opposition to Obama isn't disquieting. I can't quite fathom why they think he's some socialist radical (well, maybe they listen to Gingrich too much) when he's been running the country from a fairly central (some would say centre-right) position.
I think he's distrusted and seen as an outsider myself, but I wouldn't say there's widespread racism of any sort.