Planting a big wet kiss on every attractive person you meet is hardly proper social etiquette, and when you look at the number of bacteria in the average human mouth — more than 500 species per person, according to experts — it’s no wonder why.

More than 500 species equals billions and billions of bacteria living on every slimy surface, dark nook and inviting cranny of the human mouth, but that does not bother the kiss-happy students at the University of Michigan-Dearborn, who recently participated in a live lecture with touring kissing “expert” Michael Christian.

Christian, whose credentials are shaky at best — he’s an English teacher at Boston College — is the author of four books, the most recent which is titled “The Art of Kissing.”

Of the 200 students who showed up Wednesday to see Christian speak at UM-Dearborn, only three men and two women were willing to lock lips for educational purposes. According to an account of the lecture in the Detroit Free Press Thursday, Christian asked if anyone in audience at the jammed auditorium would volunteer. After much hesitation, a nervous 17-year-old from Eastpointe raised her hand.

Christian then led the students through an hour-long presentation on material from his book, including techniques and variations on 30 different kisses.

University of Wisconsin sophomore Craig Schiller thinks Christian’s lecture would go over well with Madison students. When asked if he would volunteer to demonstrate, Schiller first made sure that Christian himself was not the one who would demonstrate techniques, and then replied, “Yeah, I probably would.”

Christian delivers his PG-13-rated show full-time to college campuses across the country. The student activities board at the UM-Dearborn brought him in for an undisclosed fee.

When asked what she thinks of Christian’s lectures, Linda Roberts, associate professor of human development and family studies at UW, responded, “What gives him the authority to lecture on the art of kissing?”

Just what exactly it is that qualifies Christian as an “expert” is yet to be proven, and as far as Roberts is concerned, Christian should clarify his credentials.

“For those of us who actually do research and lecture on these type of relationships, I would like to know if he did any research to back up his theories,” Roberts said.

Roberts said that communication is critical in kissing and sexual situations, and she is concerned about the lack of conversation prior to physical intimacy with most college students.

“There really is very little conversation involved in most interactions,” Roberts said. “The movies don’t tell you how, communication classes don’t tell you how. If he is showing students how to improve that aspect of kissing, then that would be a good thing.”

Christian, whose voice has been compared to that of Woody Allen’s, is a small man with graying hair who claims his lecture covers a variety of topics, including tongues, braces, electricity, giggles, first kisses, racing hearts, tears, caresses, earlobes and hickeys. More important, Christian says that he is there to “promote the beauty and grace of one of humanity’s most thrilling gifts.”

Sophomore Schiller is not impressed.

“I’m gonna come up with ‘The Art of Hugging’ or something,” he said. “I can’t believe he gets paid for that.”