Probably less than ten.

Zero times! I did once wear greyface™ for a school play, to be a chimney sweep.
@previous (Kook !!rcSrAtaAC)
There are three known incidents. It seems likely that there are more we just don't know about yet.
@previous (Fake anon !ZkUt8arUCU)
Which seems like a very high amount
@previous (Kook !!rcSrAtaAC)
I agree. I prefer politicians with zero documented cases of wearing blackface.
@1,042,726 (Fake anon !ZkUt8arUCU)
a lot of older people don't seem to get that blackface isn't cool
@previous (jodi !RwordOooFE)
That's true but probably because their parents thought minstrel shows were the pinnacle of comedy.
@1,042,742 (jodi !RwordOooFE)
He was 30 wearing blackface, wasn't he? The same guy that scolded a woman for saying mankind instead of peoplekind. It's also being described as wearing "face-darkening" by the media, funny how that happens when it's a lefty cuck.
Can you imagine if Trump did that?
@1,042,761 (jodi !RwordOooFE)
Not everyone agrees with you.
Reception
In 2010, SciFiNow ranked this the ninth best episode of the original series.
Zack Handlen of The A.V. Club gave the episode a "C+" rating, noting positively the aliens' makeup and some "good moments", but also noting that these were outweighed by an overpowering message. In their compendium of Star Trek reviews, Trek Navigator, Mark A. Altman and Edward Gross both rated the episode as mediocre, describing its message as obvious and heavy-handed. They did find some redeeming moments, such as the climactic chase to the ruined planet's surface and Gorshin's performance as Bele. This episode is noted as one of the top ten Star Treks that takes on the topic of tolerance.
In 2016, The Hollywood Reporter rated "Let That Be Your Last Battlefield" the 11th best television episode of all Star Trek franchise television shows prior Star Trek: Discovery including live-action and animated series but not counting the movies.
A 2016 article in The New Yorker noted that this episode was a dramatization about slavery and racism.
In 2017, ScreenRant ranked "Let That Be Your Last Battlefield" the 7th most optimistic episode of Star Trek television, pointing out the crew's reaction at the end.
In 2016, SyFy ranked guest stars Frank Gorshin as Bele and Lou Antonio as Lokai (the black and white aliens) as the 10th best guest stars on the original series.
In 2018, Collider ranked this episode the 12th best original series episode.
In 2018, PopMatters ranked this the 19th best episode of the original series.
@1,042,769 (G)
> mediocre
> heavy-handed
> C+
add to that tone deaf and mildly racist and I agree