[mewpmewp2]

Yes, also to be clear, I am not from US and neither am I a native English speaker, but to me it's obvious that in professional or business context a person must put effort in to have seemingly clear and formal English, unless they are known as this highly skilled, experienced and an eccentric character so they could potentially pull off writing in however they please.

So I would imagine that any deviation of this expected norm would yield in a result that might be perceived as more "stupid or lazy", whether it's street dialect, US southern, redneck dialect, teenager dialect, mix with other languages or otherwise.

So my point is - that it's measuring a correlation from the standard, professional, business English, rather than it being anything to do with racism.