I'm in agreement with EntAllat here. Trip and Malcolm kind of remind me of sailors in those old World War II movies--the guys come into port and tell tall tales to impress the local girls and hopefully get a little lovin' before they ship out again. It's still early in their mission, so even though Archer indicated that dating is allowed on the ship in "Breaking the Ice," neither Malcolm nor Trip may be willing to push that boundary of getting involved with someone they work with, especially given A) their positions of authority, and B) they may not be ready for a long-term entanglement. I think the reality is, single guys in their situation are looking for only one thing: a hookup with a woman looking for the exact same thing. It would be understood by both parties that he's not going to call her tomorrow or next week or ever, so it really doesn't matter what Trip and Malcolm tell their dates, and I can see them having a little fun with that. They would probably also be operating on the premise that the women don't care if it's true or not since they're never going to see each other again, and are probably a little full of crap themselves. (Turns out this was true in spades.)
Consider also: Trip is recently single a la Natalie's "Dear Trip" letter. And we know from "Shuttlepod One" that there have been a *lot* of ladies in Malcolm's past. Not that this makes Malcolm a skank, but he's obviously not afraid to play the field, and there may have even been some encouragement from him that Trip should, too, given his unattached status.
As for letting their guard down, well...that happens when you drink. They weren't on duty, things seemed to be going really well with the ladies and it totally looked like they were going to get some, so the appearance of any threat probably appeared minimal at that point. Remember, this is their first experience in their big galactic neighborhood. They don't have much reason to suspect that these women are going to morph into two alien dudes because aside from the Suliban, it's outside their experience. Plus, as far as I know, I've only really heard of prostitutes rolling a john. I imagine it could happen with random chicks met at bars, but I don't think you hear about that so much.
Another thing Mr. Smith brought up in the chat: leaving Trip and Malcolm in their underwear. I mentioned that it was probably done because the humiliation factor would decrease the probability that the victims would report the crime in a timely manner, if at all. What I didn't mention is that the only reason they were even left with their underwear was because this was shown on prime time broadcast television.

Most of the stories I've seen when prostitutes do this, they take everything. The guy is humiliated, he can't call the cops and make a police report because his wife (or whatever, if he has one) will find out, especially considering that prostitution was involved. (Even if he just said it was a date or random hookup that's bad enough.) The guy will more than likely call a buddy and have him bring clothes and money for the hotel bill (or wire money if he's far away) and just consider himself lucky to be alive and his secret intact. He'll cancel the credit cards and when he gets home to his wife he'll make up some kind of story about a mugger or a pickpocket to explain it all away.
In Trip and Malcolm's case, there's no wife at home to upset (unless you count T'Pol

), but there are probably "conduct unbecoming an officer" regs and sanctions to deal with, plus just the humiliation of EVERYBODY knowing what happened to you, and at the very least, a lecture from an irritated captain about the dangers of drinking too much while on leave and the possibility of future leave being jeopardized.
And one other thing to consider: this probably isn't the first time these chicks (alien dudes) have done this. They are probably just as good at what they do as Malcolm is at what he does. They do their thing by being very observant and saying all the right things. They are professionals at getting people to let their guard down. That's how con artists work. Even police and security professionals get fooled. Remember, Ann Rule was a police officer, and she had no idea that she was sitting next to a sociopathic serial killer when she and Ted Bundy worked a crisis hotline together. Even professionals can be fooled.
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