Personally, I only catch myself saying nigga around the friends I grew up with (we are all black and went to public high school). I
never say it around any other friends and it would be very distressing if I heard it from any one of them. There was one dude in undergrad, had doctor parents and looked like he was straight out of the Wonder Years and shit, who liked to drop the word casually.
Needless to say that he was pretty close to getting the shit beat out of him when he dropped it on the wrong people at the wrong time.
I'm training for work on rural Missouri. Everyday I hear terrible racist white men say the word 'nigger' very casually. It scares me and depresses me to no end.
I had a probate case several years ago that involved a family from rural Missouri (and I mean
rural), and a family member didn't approve of her son's interracial relationship.
She left a hot-ass mess of a voice mail, but ended it with "she's a nigger! and I don't mean that because she's Black, because I like black people, but because she's dumb!" This line of thought is hauntingly common (and still astronomically stupid reasoning) in the super rural areas.
And this is not withstanding how another attorney loved to call me "boy" when I was practicing down there a few years back, but that is neither here nor there.