It might be too late but here are several more:

"dumb" matches "dull" nicely but is probably not the right meaning for you.

"sham" and "daft" might also work, but "flip" or "slick" seem to fit the situation better.

Although I think "glib" would be an excellent choice, "faux" might be a better one.

Good idea, by the way. And knowing the context helped.

David