I'm going to agree with the "non-holier-than-thou" folks here and say that the OP really has no business policing what another crew member does when off duty. For all we know, this is just some gimmick by a less attractive woman to get guys interested in her. I would also be curious what state of uniform this FA was in. I have flown with male FAs who just pull off their wings, ID and tie, thus leaving just a striped or white dress shirt and slacks, and head straight to the bar. Technically still wearing their uniform but who else would really know (or care for that matter). Didn't bother me at all, though it meant they were one up on me and had staked out the best seat at the bar since I had to go upstairs and throw on jeans.

I hate to say it but the OP sounds like one of those guys who likes to boost his ego by getting others in trouble. Unless this was YOUR FA and you knew she was supposed to be at the airplane in less than 8 hours, then mind your own damn business! And seriously dude, take a picture of her?! I know overnights can get lonely but that is just weird!