In glam photography, most of the pro photographers I know treat the models like Princesses. The fact is, most pro models know several other models and photographers, so the grapevine stretches out pretty far, and if they have a bad experience with you, others in the industry are certain to learn about it fast. Therefore, if you value your reputation, you act professionally during your photo/video sessions.
Also, as Dean indicated in answer to another question, for most people shooting professionally, it is fairly rare to be alone on a set with a model. I always welcome models to bring someone with them, plus invariably there will also be a make-up person, other models, or a production assistant(s), etc. onhand.
To operate efficiently, the number of people on a set is best kept small (especially when shooting video, where sound is also important), however it is fairly rare to be one-on-one with a model, so there would also be witnesses if there was anything untoward going on.
Now, I can't speak for all other photographers, but for myself and several others I have talked to that shoot on a regular basis, we rarely ever get aroused during a shoot. My mind is so focused on technical issues (lighting, composition, story board, video transitions, etc), that odd as it might sound (especially when shooting hardcore video), but sex is the last thing on my mind.
Granted, we are often working with beautiful women, but in the end it is still work. I will be honest and tell you that when I do post-production, yeah, I am very happy if I happen to get aroused, because that means I have a set/video that should have a similar effect on the people that pay to see my content. Hey, photographers are human too...
With that said though, I'm always so busy that I rarely look at my work except when I am prepping it during post-production, since I am already getting ready for the next project...
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