4) Believe it or not, there are people on this forum coming from countries which do not have a history of subjugating people based on their skin color. So, even though a lot of you may have that scarring, some of us don't. Are we supposed to apologize for that?
7) Again, things like "norms of white" are not strongly entrenched everywhere. If there is a bit of white guilt involved here, why am I obligated to participate in that?
This is a fair point, however I don't think a single cultural group on earth can wash their hands of racism; at some point
everyone has subjugated another group for political or nationalistic reasons, or has
been subjugated by another group for some reason or another.
Straight white males are undoubtedly the worst group when it comes to this, and I accept my argument is clearly eurocentric, however I don't think the race of the person making the joke fundamentally alters its legitimacy or illegitimacy, unless it is self-deprecating (which in and of itself raises a nasty little structure-agency debate).
6) There is also a subtle racism when you can describe things as "white" (white lightning et al.) without being offensive, and not as "black" without not.
You assume I don't have similar concerns over this, although describing someone as 'white' has nowhere near the historical connotations of oppression that 'black' does. You're still foregrounding race, which I see as being incredibly pointless, but you're not foregrounding a characteristic historically used to oppress.
Furthermore "I don't think it's racist" isn't definitive proof that it isn't racist. You can't tell somebody of a different race what they should or shouldn't be offended at, especially on the grounds of race. That,
in and of itself, is incredibly racist.