Saudi Arabia is a pretty safe country in spite of what you hear. You just need to avoid bad times and bad places. Black Americans are not bothered at all.
SE Asians? Depends on their job. And citizenship. But mostly OK. One needs to understand that Saudi is a place where the locals are busy and so are expats. Everyone is doing his own thing. Most people are just not bothered and don't care about each other. So, they are treated like here in the US. Bad treatment? Well, if they are cleaners, they will be treated as cleaners. But most are just left alone.
Americans are treated very well. They are there to protect the Saudis. And Saudis know that.
But again, keep in mind that there's no "treatment" per se in Saudi. Saudis come to work, do their job, interact with people in a minimal way and go home. And expats go home.
Take the contract! I loved working in Saudi- the best place in the world in which to work!
... would argue just the opposite: Colorism may in fact elevate to the status of race or nationality. To use your very example of Brazil, there is no "one-drop" rule, unlike in the US. While a black Brazilian may..
Oh, yes, I am fully aware of it. That is the Latin American brand of racism. Some argue that it's worse than what we have in the USA because at least in the US, we have AA; there they don't because allegedly they don't have racism and everyone is Brazilian.
The same in Saudi-- everyone is a Saudi but some are more Saudi than others.
The same in France- everyone is supposedly French but if your name is Mohammed, yeah, you are "French", yeah-- in your face you are-- but behind your back, you are just a dirty Arab.
Many even prefer the US system because at least it clearly puts people into sub-nationalities, assigns a certain official identity to them and then there's attempted ( sometimes well and sometimes not so well) protection and help to make those groups advance. The United Negro College Fund, NAACP, various hyphenated organizations and strong anti-discrimination laws all have helped many people-- this is why Obama was allowed to run and then you have all these black mayors and black senators, judges etc.
But since the above system is just original English racism turned inside out, it still divides people socially more. If you go to Latin America, you will see that on a grass root level, everyone mixes much more and there's colorism without ethnicity. Problems begin when there's jobs, money, positions involved.
Hard to explain, you need to go and live there and see what I mean.
Suffice to say that you can't tell on the phone what race a person is.