You're not the only one-- this has been extensively discussed in the "simple marking for items" thread, where the core devs agreed that something like color-coding should happen. This, however, appears to be a low priority. In the meantime, I think that a mildly enterprising coder could add this functionality to one of the Zotero plugins rather easily, probably by creating special-use tags to mark the statuses, and tying them into a drop-down menu on the items. The only particularly hard part would be coloring them in the interface-- but fbennett has already figured that out for his experimental duplicates flagging system, so said enterprising coder could borrow from fbennett's work.