As an LMT, there are strict rules that if any client even remotely gets "sexual" (either physical or verbal), we end the session immediately. Physiological repsonses like hard nipples, goosebumps, erections, are taught about in school and how to deal with it. Therapists are told never to refer to themselves as 'massurers' or 'massuses', massage oil is not 'lube', and a table is not a 'bed'. Therapists are instructed to correct clients to use the correct terminology. Therapists who are found to engage in "sexual" relief, lose their license, reported to the police and are typically blacklisted. Most city's have ordinances against massage therapists from working from their home.
As an LMT, you can't but help think about the whole sexual situation when touching someone, not because we've been instructed on how to recognize it, but because we humans are sexual creatures. I think the therapist is just as vulnerable to thoughts just as the client is, it's just we have to be professional/clinical about it.
Just a fun little story on an experience as a therapist: This athletic chick comes to the clinic for an appointment. This is my first time working with her, so I'm not familiar with her body. Everything seems to be cool massaging her back and arms (it's nice to get to work on a defined body). I get to her lower body and fold the blanket to reveal her thigh and I can see she's wearing a g-string, but I had lifted the blanket just a little too high which I glanced at her crotch (not on purpose, but you know how if some one flashes you, you can't help but look?). Her cunt looked kinda 'puffy'. I smile (she's face down, so she couldn't see my smile), but I'm a professional, so I remove that naughty thought and continue onward. I also notice that she's got kinda skinny legs (I've got big hands -- so I typically get the fat clients), so I'm rolling and kneading her hamstring and work my way up to her glutes. I start working back down towards her knee and when I reach for her adductor (inner thigh), my finger brushes against her cunt. I was utterly mortified!!!! I just keep moving on down to her knee and then I said, "Sorry about that". She replied, "It's okay."