Is that intended?

It isn't about reputation, its about if you helped Caesar or not........I think.

this happened to me as well. I think they don't really go after you unless the Don't Tread on the Bear! quest gets activated.

If boone is with you it may screw it up, If not thats a bug.

Off topic but as anyone noticed if your are wearing T-51b Brotherhood armour the Powder gangers don't mess with you? I say T-51b brotherhood armour and not just T51b because there is a difference. Same armour but one has the BoS markings.

boone is not with me. My game is patched and up to date...could it have anything to do with me playing in offline mode with steam??

this is not exactly a bug.

the game is designed to allow you to complete quests for different factions and it is not until the late game when you move past the point of no return with NCR.

If you want the NCR to turn red, just attack any of them when you see them.

They will go back to yellow if you leave and return to the same area later, so that you can talk with them and complete the NCR quests if you want to.

Here is a little bug I found that will get the NCR to attack you on sight:

First, go kill a legion member, and take his armor.
Second, make sure you have pre-war business ware in bad condition.
Third, repair that pre war business wear WHILE STILL WEARING the armor.

The game takes it as you are still wearing the Legion armor, and every NCR will attack you.
I think this is a bug because I only wore Leather Armor Reinforced and they still attacked me once I did above^

Are you on the strip? It is my experience that they remain neutral on the strip.