Clothing Stars and Hearts

ExpectoPatronads

How do I know which clothes give stars and which give hearts after I've bought them since the icon disappears from purchased clothing?

Flickertail

Doesn't matter. The game is looking at the total number of stars/hearts you've earned by buying stuff when rating you for a date or appearance/photo shoot. If you don't meet muster, there's a number in the lower left corner that indicates how many stars/hearts you have vs how many you need to get the bonus gold star.