If you ever get to meet your idol, I think it is safe to say not to do this. They are not there to snog you. If you try to get a kiss, then you are most likely automatically put in the creepy section no matter if you were cute to them 5 seconds ago. They are there to do a job, have to meet thousands of fans, and frankly it’s embarrassing to be seen getting puckered up by a guy in front of a lot of people.
Also, it makes the Doctor sad, that’s his girl there. No one touches her if she does not want to be touched!