So I walked in to Solitude dressed in full stormcloak gear went straight to the imperial barracks strolled around a bit and no one batted an eyelid. On the other hand even wearing a full set of plate armour guards seem to know exactly what guilds I'm in. In any other game it wouldn't bother me but Skyrim is an RPG this kind of thing is supposed to be important.

Yes, npc's don't know enough and I'd like disguise a la New Vegas. They react to you naked, though

People have said to me "That stormcloak armor is starting to get on my nerves." And "I hope you got that armor from a dead legion scout." So it seems like people assume that because you're wearing faction armor, you're not necessarily part of that faction.

I agree with op on this one, only the guards seem to notice what armor your wearing and comment on it. When I delivered the forged stormcloak orders in Dawnstar I did it wearing my Heavy Imperial Armor just to see if they would notice, but they NPC didn't bat an eye, I thought I would have had to explain it or something or make the taking of the fort more difficult because he knew they were forged or something. I think they really dropped the ball on this, the should have spent less time scripting random comments from guards about what I am wearing, what my skill levels are, or what I am carrying and more time into having NPCs that really matter notice this kind of stuff.

If i walked around in a US airforce uniform wouldn't you suspect i was in the airforce?

Only anonymous town guards will react to anything. Everyone else is oblivious to everything.

I also waked into Solitude in full imperial officers gear and immediately got told to keep my hands to myself sneak thief. What he should of done is snapped to and called me sir or said I dont recognise you lets see your papers. Its not a game breaker but it does break the immersion a bit.

I'm head of the Dark Brotherhood and wearing their gear. Some guards will say, "It's not true what they say... about you and the Dark Brotherhood, is it?" whereas others will say, "Psst! Hey, I know you. Hail Sithis!" In fact, a jail guard in Falkreath said the latter to me, so I decided to talk to him. His very next line was, "I know you. In the name of the Jarl, I command you to stop!" Somehow I had a 40g bounty in Falkreath. Seems like I always have a bounty there, lol.

Im a stage three vampire with an undead master necromancer thrall in tow.
I come across a Vigilant of Stendarr.

And.. Nothing.

I should have been attacked on sight.

These kind of things in the game do not make me happy. I understand that for casual players it may be a nuisance when you get killed solely because youre wearing the wrong gear or have made the wrong choices/ allies but, well, thats a learning moment.
When it gets to the point that nothing matters because no matter what the game will go on as if you didnt, it feels a bit like Im on rails that I cannot deviate from.

Recognition of "the Dragonborn" and his choices is sorely lacking..... agreed.

I doublecrossed Ulfric and purposefully went to his palace afterwards to see his reaction. Everyone acted as nothing happened. Galmar Stone Fist acted as my bestfriend, Uflric wished me well saying "May the gods be with you"

The Civil War quest line leaves a lot to be desired, unfrotunately A wonderful, missed opportunity.