Comment by _asummers

I was rather displeased with the built in color scheme on a dark background, so I changed it to a nice purple and removed the underline:

    (set-face-attribute 'slack-message-output-header nil
                    :foreground "#C080FF"
                    :underline nil)

Binding slack-select-unread-rooms to something useful is a good choice. I have it bound to M-T.

If your users have avatars in their usernames, makes them go away in the source of slack-user-message.el in slack-message-sender with

    - (status (slack-user-status (slack-message-sender-id m) team))
    + (status "")

I found people with stuff in their statuses made room names distracting, especially with group chats In slack-im.el, in slack-room-display-name,

    -  (format "%s %s" 
    -    (slack-room-name room)
    -    status)) 
    + (format "%s" (slack-room-name room))

I am not good enough at Elisp to figure out how to make these hooks and I've been a bad open source person at opening an issue on these.