YES you can get aids from Salivia, GALLONS AND GALLONS WORTH. Pretty UNREALISTIC if you ask me.
Pretty mucn the ONLY way to get aids is through open sores/cuts/wounds that come in contact with the disease.

Even then, it is a low chance of getting it.

Shit you can even have unprotected sex with someone with aids and there is still a low chance of getting it. Of course that is a very stupid idea in the first place, I am just using it as an example. Plenty of people in this world have had sex with infected people without realizing it, only to find out later..and then get tested and it is still negative.
Never should you risk it, I am just saying...it is pretty hard to get aids. You aren't going to get it from making out with someone with aids, unless you both have a canker sore or something...then theres a slight chance. But really, be realistic here guys...not smoking with someone who has aids? Jesus, they're not lepers!