most ppl doing digital blackface are usually 4chn nikkas or other alt righters doing a terrible job of trolling actual black people. They are blatent due to them being socially inept, sheltered and usually (almost always) retarded. (plus a lack of knowledge on current black culture)
If you see any of the following, it's probably a 4chnner in disguise
• posing as a young black woman with a offensively stereotypical name like lakiesha
• using a lot of black stereotypes like single parents or crime, being on welfare or a father in jail
• using terms like whitey or 4chn meme words (check knowyourmeme and they'll tell you)
• following/retweeting 4chn or altright twitters (look for a pepe, a green cartoon frog) or RW political shills like Ben Shapiro
• saying blatently racist/left field shyt and then hiding behind their "race"
• complaining about Jews, Muslims or European immigration(99% of black people do not do care or even acknowledge Jews/Muslims while Altrighters/NeoNazis want them all dead)
This shyt was highly apparent during the Trump elections on Twitter so keep an eye out and use the report button