Have you ever had to use a disguise to infiltrate a factions settlement/HQ and do something there?

I've recently had to dress as a CL member just to free the Weathers family in Cottonwood Cove (Doing all quests that give CL Infamy before getting the Mark) with Boone watching from the Overlook, the Aurelis almost caught me. I wiped them out just after that by sniping with Boone for 'Eye For an Eye'.

Boy I love the Hunting Rifle with a scope.

I used one to walk into the Strip free of charge. (Was to poor back when I didn't understand Caravan.)

Si, I took care of the entire McCarran regiment after becoming Vilified by NCR. Great fun stabbing troopers in the back.

Oh yeah. I've gone undercover as a Great Khan before and assasinated Papa Khan for the NCR, I've done rp's where I'll dress up as someone from the Legion or NCR to infiltrate one of their camps and wipe them out from the inside, all kinds of stuff like that.

I once disguised myself as an NCR soldier to get onto the strip, another one would be when I killed everyone at cottonwood cove (I told the weathers family to leave while they still had thier collars on, that one never gets old) and then disguised myself as a centurion and assassinated Caesar. I remember when I was so misguided.

On my most recent playthrough, a psychotic cannibal who snaps after the whole "being-shot-in-the-head" thing, I use NCR and Legion disguises quite often to avoid trouble (or get a quick snack). I also had a Legion spy playthrough that always had a NCR mechanic jumpsuit handy. It's amazing where you can get into with some shades and a jumpsuit!

I must say, disguises must be one of my favorite new things added in NV.