I connect (or at least try to connect) to slack via XMPP.
I know, I know, that is of the devil.
Anyway, it would seem that XMPP is not tracked properly at the system status page here:
https://status.slack.com/
I have contacted support on this (to them I am guessing non-issue), and have been told to reconfigure my client.
Not that my client could not be at fault, but I find it funny when it does work some days, and not others.
So, long story short, if you rely on XMPP for some of your bots, you might not be getting the whole story.