This is both an interesting and timely topic for me. I recently had an online experience where I was the patient. For those of you who know me, you know whether I am in the patient or provider role I make the experience as real and realistic as possible, and I do, like most have some flexibility as far as setting, content, scenario, etc. But, I also like most have my hard limits. I always clarify these limits upfront and I do not expect, nor will I allow them to be crossed. It's a closed border, with a very secure wall!
The person I was playing with online violated one of my hard limits not once but twice, and the same one! I accepted his apologies the first time and days later we tried again and he did the same thing! Whether it's online or "Live", if you are a good role player, in your head it's real and in your body it can be, too.
The moral to the story is not everyone can be a great role play partner, BUT everyone needs to respect peoples' limits especially when they are clearly stated. If you have questions or modifications you would like to have made, ask! Don't just go ahead and test the waters and think the other person who may be enjoying things will just tolerate it.
So, bottom line, for me the most important and critical element to role play exams live or online is open and honest communication combine with mutual respect.
Play safe!