I just use smileys. I know that some people see them as childish/immature/unprofessional, but especially in a multi-cultural environment I prefer to be safe.

Irony, sarcasm and humor don't scale well.

Me too! Just to keep it good humored. If you put a smiley in an issue or a slack message it helps keep the recipient happy

How I sound when I reply: :D

How I look when I reply: :|

Yeah, I always tried to include an emoji at the end of my messages just so that it won't be interpret differently.