I would work on the things you can or want to change (clear directions? easy grading?) and not worry about subjective things like your allegedly phony, see-through smile that don't have anything to do with anything? Your smile doesn't have anything to do with whether they learn/find you to be a good instructor. Think of all the angry/serious To-Sir-With-Love stories? It's not a popularity contest, it's a how-well-do-you-teach contest (but, like you say, who needs idiot contests).

Have you ever started the first class with a "discussion" of what they want/expect to learn from the class and "ideas" how to do that in an interesting-to-them fashion? I don't know how married you are to your tried-and-true syllabus or notes but maybe spend a semester revamping based on what the student's say they want at the beginning? You "know" the material they should know but they can tell you how they learn and what interests them and then the challenge is presenting the material in a fashion that grabs them.

When I took my senior-level Communications/"Listening" class, for example, as part of a project I had to create I posted a couple pictures of people engaged in conversation, and had the other students/friends visit my web site and choose from a multiple choice list what the people in the pictures were thinking/saying/feeling :-) I was studying differences between male/female respondents, what they'd choose! I loved it :-) and the people at my work I dragged in to try it, etc. did too.

I think interactive is big with young people; movies, polls, games, "translations" (I did another project in that class that did something with Alice in Wonderland! Talk about your "communication" problems :-)