No one can tell for 100% certain, but these guys gave you some good tips.
Pcray, it's funny you mention the crisp line on the anal fin of a native/wild brookie, because I caught my first that had a rough edged one. still clear edge but it was not a straight line. Every other fish that day perfect condition fins and everything else. This fish perfect, except that one little thing. Wilderness wild trout, Not stocked, ever, and a long ways off the road, and a physical barrier preventing it from coming up stream. Was a very very old fish.
Another point to note is that club stockings have gotten crazy in recent years in regards to how "wild" and good the fish look, and they only get better as they hold over.
Also I have a pic of a wild bow with broken red streak, if you guys want to see that bad. Bows really are tough.
I also caught a bow the other day with spots that wrapped clear down and onto the anal fin. We were fishing for brooks and browns, and I ended up pulling two really good looking ~10" bows out in addition to our intended prey. I was skeptical and found out the stream was actually on the stocking list. That said, we caught several wild fish but several that blurred the line. Would be interested to know if the spot thing is sure fire or not.
Something to say with browns, usually with small to medium fish, spots will be perfect circles, not a molted pattern or spots that overlap/run together like you see with stockies. Not sure if it was mentioned, quickly skimming the thread.
Behavior of a fish is also something to mention. Especially with small streams/clear water. Where was it hiding, how did it hit, how did it fight, how did it act when released. Nothing definitely, but a piece to the puzzle if you're not sure.
Its definitely tough. Great discussion in here.