The best argument against democracy is a five-minute conversation with the average voter.
An appeaser is one who feeds a crocodile, hoping it will eat him last.
Relative to the oblivious person's perception of the world, such obliviousness is probably good because it shelters the oblivious person from a difficult part of the world.
Relative to the oblivious person's inevitable interaction with people who are aware of the stereotype, it's probably bad because that person is probably going end up getting their feelings hurt when someone tells them how ignorant they are.
Relative to those who are harmed by stereotypes, it's could be good or bad. It could be good in the sense that someone who doesn't even know about certain stereotypes won't intentionally perpetuate them. On the other hand, it could be bad because that same oblivious person could be complicit in the perpetuation of such stereotypes in their ignorance.
In general, however, I think people ought to be aware of what's happening around them. As a person thing, I find it nearly intolerable to deal with people who aren't ignorant of things that are incredibly pervasive.
"It ain't what they call you, it's what you answer to." - W. C. Fields
I fell in love and married Selena (my second wife) because she is my "soulmate".We connect in ways that me and Allison didn't.(mind you,Allison was a good wife and mother,but she wasn't the passionate fun-filled woman that Lena is).
Skin color never played a part.
No, it's not good. I was in a conversation with a black guy at work up in Michigan, and I said the word "boy" to him (not in a racist fashion, because I wasn't even aware that "boy" wasn't allowed to say). It nearly ended in a fistfight.
Also, racist jokes aren't nearly as funny if you don't know the stereotypes.
To answer your question, I think most of the time people who don't know a particular thing is viewed as a negative racial stereotype, if they're of adult age, are either doing so based on feigned ignorance or essentially CHOSEN ignorance (IE they've heard it before but just never process it in such a way that they'll recall it quickly).
I think that's the case with the vast majority of such stereotypes, especially the more "common ones". That said, I say "majority", because I do think sometimes you may just not realize. For example...
It's similar to when I first heard that "Gypped" was a slur referencing gypsies.
I do understand that there's a great difference between believing all racial stereotypes are inherently bad or shouldn't be said or talked about or are true/untrue or whatever other deflection people are using to try and refocus the topic....and simply answering whether or not people feign the knowledge of most of said stereotypes.
"I am appalled that somebody who is the nominee...would take that kind of position"
"A court took away a presidency"
"...the brother of a man running for president was the governor of the state..."
It's horrifying because Trump is blunt instead of making overt implications.