If you were kissing ("making out" with, for an extended period of time) someone who had been drinking (about 10 rum & cokes); is it possible to have a positive EtG test from the transfer of saliva?

Very, very unlikely. EtG doesn't have a long life in saliva and is eliminated within hours. In addition, orally consumed EtG from external sources doesn't seem to be absorbed into the system of the recipient (while EtS is). This is just an observation on my part, based on only one study, and the specific concept you describe has never been tested.

Hoiseth, 2008 (http://alcalc.oxfordjournals.org/content/43/2/187.full?sid=5cf8d521-9b3e-49a3-a597-a10c9f4ed2b1)

Thank you! I appreciate the response.