Figures that you are not from Central America.
Actually it is “El Negro”. That is indeed not making a remark about a black adult being called a boy.
Others that I have heard, that once again can be turned into insults depending on the context are: Oscuro, bruno, moreno, negruzco, atezado, africano, mulato.
It’s not really all that affectionate if the person doesn’t like it. If these people think he’s a prissy pig for having a problem with it, then how much affection did they have for him in the first place? Apparently they only like him if they are allowed to call him a nickname he doesn’t like.
I know my uncle loves me. That didn’t stop me from telling him that one of the nicknames he had for me wasn’t one I liked. And, of course, since he loves me, he used a different one–an older one I’ve always liked.
Cultural sensitivity goes both ways. When it comes to what someone prefers to be called, it makes far more sense to go along with their culture than to impose your own.
Yes, this is just my opinion. But I think it’s a pretty good one. I hate this idea that you’re just supposed to not say anything when something bothers you. Sure, maybe sometimes it’s not worth it. But, most of the time, it’s fine. We need to communicate more, so we find solutions that make everyone happy, instead of having one person unhappy because they are afraid to say anything.
You tell 'im, Bigtito!
Here in Panama the polite term is “moreno.” I knew a woman whose nickname was “La Morena.”
My understanding is that calling a person “negro” here is a bit impolite. However, “negrito” is OK. The diminutive softens it.
Latin Americans are much more accepting of descriptive nicknames than Americans are. People go by “Gordo” (Fatso), “Flaco” (Skinny), “Fulo” (Blondie), and no one thinks much of it.
I was amused when I saw the list the security guard at my apartment had of the tenants, and I was simply listed as “Gringo.” 
Also, once I left my Jeep at a garage and when I picked up the keys I found them labeled “Cherokee - Gringo.”
And as I noted, I agree, the case I mentioned was not a soft remark and had other disrespectful lines towards then president Obama.
I know a Salvadorian woman whose given name is Morena…although she really isn’t.
In Spain, yes, but not in most of Latin America, where the sound is much “softer” (more airy, closer to an English “h” – in other words, less guttural, further from a German or Scottish “ch”).
As true 11 years ago as it is today! 
Yeah, you apparently never get tired of repeating this anecdote, you already told it only 11 years ago. It’s incessant, I tell you.
Now they call him “Gringo with Alzheimer’s”.
Not that it’s any landmark in art much less definitive, but in the TV series ‘Queen of the South’ the heroine’s Mexican-American ‘white’ looking boyfriend (played by Jon-Michael Ecker, an American of partly Brazilian descent) is, to everyone, ‘Guero’. OK besides the initial disclaimer it’s a show about the criminal world, which is generally not where ‘correct’ speech about race etc is expected, but anyway.
Gringo viejo.
Is that Spanish for “Bill”?
An anglo represented Mexican pronunciation of güero as sounding like “Where-oh” not “Kwei-do”? Really?