I always smiling during my dancing and even during my training so I remember to do it on the floor. I did over the week-end take up hold with a closed smile and then when we start dancing I do a smiling showing teeth. the more you do it the less fake it becomes
That is good advice.
Or the better you get at faking it - possibly to the point that even you don't know which is which. That's exactly my point because a fake smile is not convincing happiness - surely we all know people who have a permanent 'smile' that totally lacks any emotional content. Its disconcerting and can be even alienating.
The question, I guess, is if the same outcome happens on the dance floor. I think the judges just see a couple who are dancing but since almost everyone has a fake smile it looses its impact. However, a couple that is really enjoying itself will, IMO, stand out amongst the fakery.