Upon reading this without context, it seems as thought the character speaking is being insulting towards others. The word fool can have a negative connotation to it. However, for centuries, and still today, the word fool has more of a playful and humorous tone. Such is the case with this lemma from the text. When Rosaline calls the men fools, she’s referring to how foolish they were to believe that they could trick the Queen and her ladies by wearing masks.
Notice that before indirectly calling the men fools, Rosaline says that she wouldn’t dare call them fools. This is probably because she understood that her comment could have been taken the wrong way. By adding that she doesn’t wish to call them fools, she takes away the negative tone from the word. There is irony however in her statement. She says she doesn’t want to call them fools but does it anyway, just not in a forward manner.
This lemma doesn’t have some underlying or hidden meaning. The character means exactly what she says. She does however do this with the intent of letting the men know the ladies were not amused by their disguises and to make mockery of them as well. The subtle way she does it stresses the different meanings the word fool can have. It also serves to make the men think of what they’ve done.