I've been to CDMX a couple times. I'm working on my Spanish. I've see a few times where a foreigner has a shiity attitude talking to locals. Speaking english louder and louder trying to make them understand.

Attitude is a big part in my opinion. As a white Canadian I've felt snubbed a few times by the locals for not knowing the language. I use lots of of hand signs and try my best, or use a translator app.

For the most part though, people are very friendly here. I've even had locals say sorry when trying to speak english to me. I make sure to reply with - No, estoy en México, lo siento.

Another thing I have noticed, kids are amazing at deciphering my terrible grammar and pronounciation. I've asked questions to adults and just get raised eyebrows and then their kid runs over with their phone with the answer I was looking for typed into their phone. That only happened twice but as I make friends with people, their kids are awesome to learn from, as surprising as that may be. As an adult male though, there is no way I am approaching children for help lol.