afk flags go away for me whenever i cast spells on my shamans. perhaps its instants that don't clear the afk. Putting someone on /follow though definitely doesn't clear AFK.

whats really fun in AV is if someone starts harassing you in chat about being a multiboxer, you can use all your chars to report them as AFK. It only takes 3 or 4 to give them the debuff. I find it very satisfying to suddenly see them yell in chat about who is the **** that marked them inactive.