I'll throw in the opinion of another dude here...I would be like you and be upset if my girlfriend was doing this, but only for one reason: the fact that I would never do that to her.
We're human and its in our nature to find people of the opposite gender attractive, so that I can't blame her for...thats the only reason girls went to see that movie...if it was the same movie and story line with a bunch of female strippers, you'd be lucky to see 25% of the audience females. Saying omg he's hot...or whatever I don't think is all that big of a deal, as long as she doesn't say it 15 times like your girlfriend seems to be doing.
I think the biggest offense is she's looking for these guys naked online...thats what's really disrespectful. Honestly, she seems like an immature little school girl, but that's expected, assuming you are indeed under 18. As you get older, you'll experience more mature relationships and girls who won't do this to you.