petallus, essentially, yes. Most racism is deliberate. Sometimes it is unconscious. Either way feeling offended/outraged doesn't change anything. Discussing what things are regarded as racist and why does change things, given time. Attitudes are changing because of education rather than because people take or don't take offence. Even with racist remarks, what one person finds offensive won't always be the same as what another finds offensive.
For example, in Oxford I had two friends from Uganda. One was a Ugandan Asian whose family had been ejected by Idi Amin. The other was a black (very black, the blackest person I ever known, gorgeous skin colour) Ugandan – I can't remember from what tribe. Anyway, the Asian Ugandan thought Brits were very racist and found racism in virtually everything. The African Ugandan said he'd never experienced any racism in Britain. And yet they mixed with the same sort of people. Knowing them both as I did (they knew each other too), it seemed to me that the Asian Ugandan made the choice to be offended by so much and the African Ugandan let things pass. He was the happier person even though his life had been tougher by several orders of magnitude than the other's. In short, the Asian had a chip (or several) on her shoulder and he didn't.
How will things change if our summers keep getting hotter
This would under normal circumstances be headline news




break here. 
