Speaking for myself only: A sexypic will make me look directly at the cover, which increases the odds of the cover text grabbing me, even though I am aware that sexypics are often used to make crap content appear more desireable.  So.  If the cover text of a book or game grabs me (sexypics or not), I will pick it up and examine it more closely.  But by this point, a sexypic will have no effect on whether or not I actually buy the thing.  That job will be done by the content.  I will leave it to others to discuss the effect of the sexypic on those sitting at the table, because Adam raises a good point.