I never read your question, Christian. But people did wear masks inside, but not in clubs.
Not sure if Mexico City would be your cup of tea. I know you're not a party mouse and there is no massage scene you would be interested in. It is mostly macho guys. But that is only from a boy's perspective. Culturally it is a great country. Who knows, you might discover a whole other side of Gay Mexico that I don't know.
And there is always Grindr.