Let's look at some great movie kisses. Everyone has an opinion on something like this. This is my girlish take. In the movies, since we are essentially voyeurs at an extremely private moment, it's not about slobbering, it's about the actors' ability to convey love.
Here are some examples featuring Ronald Colman and Charles Boyer - both age 46 in the clips. They both had magnificent voices and expressive eyes. It helps :-)
There is just no one like Ronald Colman. He had the most expressive eyes. If you want to get right to the smooch, advance to 2:00
Charles Boyer was short, paunchy and wore a toupee. In real life he was thoughtful and bookish. One anecdote is that when Bette Davis saw him on the set of "All This and Heaven Too", she did not recognize him and asked to have him removed from the set. Ah, Le Grand Charles....