Question: Someone once told me they were saying [güero](https://forvo.com/search/guero/es/) which sounds very different from what the Mexicans are saying.

Answer: 
I'm from México and I've never heard the word *güido*, at least in central area and the south, maybe in the border is something different. If you are trying to referring a person from the U.S.A. the correct word said in Mexico is *gringo*, a very common slang to call someone of this country.

In Mexico, the word *güero*, has principally two meanings. The first one, (*in a strict mode*) is a term that denotes a blonde person. For instance, [Kaley Cuoco](https://encrypted.google.com/search?q=blonde%20person&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi9hNu8wsLSAhUZS2MKHW3hAVYQ_AUICCgB&biw=1242&bih=580#tbm=isch&q=kaley%20cuoco&*) is *güera*, and [Brad Pitt](https://encrypted.google.com/search?q=blonde%20person&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi9hNu8wsLSAhUZS2MKHW3hAVYQ_AUICCgB&biw=1242&bih=580#tbm=isch&q=brad%20pitt&*) is *güero*. The second meaning is an expression to call anyone, for instance:

* *What's up man?* is the same to say in Spanish *¿Qué pasa güero?*

For that, anyone in Mexico can be *güero* o *güera*, no matter of the color of their skin, you are just calling someone.

As you can see, there are not even similar, maybe you missunderstood, or hear someone that wasn't Mexican.
Actually wedo is a derogatory term to describe either white people or mix breed white people. Loosely it's the same as being called a cracker or a honky.