When performing review tasks an option appears saying, "Flag or disagree..." but no option to disagree exists. For example if a question has been flagged as "not an answer" or "very low quality" I think I ought to be able to say, "No, I think it's fine as is." That's how I interpret the intent of the "disagree" option anyway. However, clicking on the pop-up results in only "flag" options being presented, so I have to cancel out and wander away- or is there something I'm missing?
I'm having trouble actually finding this button (possibly due to the fact that I'm a mod), so I can't verify it for you, but buried in the middle of the flag options, there should be one for disagreeing. It's not the ideal place for it, but it should be there; if it isn't, let me know how you're getting to this dialog and I'll see if I can find it.