Not all communities and rooms are created equal. Some have higher standards than others. Thus, what can be considered offensive in one room may be very well acceptable in another. What makes them different? Context.
Here's an example:
Oh wow, Lara Croft got raped?
I wish I was there too! lol
By themselves those two lines are innocuous. You say them one after the other and you get something disgusting enough I wish I could be making a different example.
I believe flag reviewing can be improved by showing a little context about the relevant message. Just the two previous messages (if any) should be enough to gauge the community's in-chat response to the message.
Additionally, good flags should be made on very fresh messages, given the time sensitiveness of the medium. A spam flag cast 30 minutes after the fact on a busy room is good for very little; all users have read and probably forgotten about the message; the only real remedy the flagger is looking for is causing a suspension.
Thus, when reviewing flags, timeliness shuold be underlined. How much time, how many messages have gone by since the "offensive" messages? Is it really offensive if nobody acted upon it in the last 30 minutes?