Green sunfish have to be among the most easy of sunfishes to identify; hell, their among the easiest of native fishes to identify. When someone posts a picture of a green sunfish and a dozen people say its a bluegill that only spreads misinformation. Now someone who reads this thread may say "oh, that's what a bluegill looks like" and ID a fish for someone else only spreading misinformation further. It's alright if you don't know what a fish is but I know whenever I look at an ID thread I don't respond unless I'm fairly positive I know what I'm looking at and I think others should do the same.
Personally I think the biggest problem is the use of common names, most of the people who venture into this forum are fishermen who have likely been taught that some fish are something other than what they actually are. Around here there are two kind of sunfishes; bluegills and sunfish. Of course the fish that locals call "sunfish" are actually pumpkinseeds but if you try to tell them that their sunfish is a pumpkinseed and that both pumpkinseed and bluegill are sunfish then they'll just look at you like you're from another planet. For a real fun time try to tell them that largemouth bass are also sunfish! I remember once I was collecting on the shore of a nearby lake and some fishermen came by asking if I caught any stonecats, I told them no, that I had only caught some sculpins. I showed them the sculpins and they said "oh, those are stone cats". I didn't argue with them. Anyway my point is that the people IDing some of these fishes may know the difference between Lepomis macrochirus (bluegill) and L. cyanellus but have their common names backwards or mixed up in some way and IMO those sort of misidentifications are more forgivable. That said I don't think we need to start IDing with scientific names only, if you look at any book concerning natives or most reputable web sites the common names are pretty much used universally. There is no reason to call a green sunfish a bluegill.
