A snake can't hear a kissing sound.. That wouldn't even make enough of a vibration for a snake to feel. They feel vibration and also vibration from certain sounds or wavelengths but they can not hear. So the snake that is smelling, or as you put it, kissing you lips after you do that, is inspecting it's surroundings. It knows you are not a threat. It can pick up the heat from your lips. It can feel and smell your breath.. etc etc..
Snakes are scientifically, biologically unable to feel the human emotion love. It's a scientific impossibility. So why is there even a question?? Thats what I don't get here. It's like saying grass is orange. The earth is shaped like a triangle. Humans hatch from eggs.. It's simply not fact and makes those people look very silly.
One could go on forever about how their snake behaves around them but it all boils down to the facts of nature, biology, and the brains ability to feel..