You know, it's very refreshing to see a lady look like she's enjoying herself.  I, for one, am looking for fun in a lady and just as a matter of personal preference usually won't book a lady who doesn't have at least one photo with her smiling.  Those who have prune-faced expressions or look like they're in agony in photos tend to turn me off and are less likely to get a call from me, even if they are stunning otherwise.