Just in time for valentines day, I discovered this interesting study. According to the Journal of Infectious Diseases, vol. 150, no. 2, August 1984, pp. 189-94, it is very unlikely you can catch a common cold from kissing. According to the journal, “Casual social encounters or kisses between infected and susceptible individuals are probably unlikely to result in the transmission of rhinoviruses.†Below is the data from the experiment
Bonus quote from the study: “During kissing the lateral margins of donor and recipient noses may also touch. [Our observations, as well as previous data] suggests that transmission resulting from nose-to-nose contact during kissing is infrequent….”