Elmire is what you might call a strong woman. And we're not talking 17th century strong, no sirree. She could go toe to toe with a 21st-century lady and hold her own. Now, this kind of "modern" spirit doesn't really sit very well with some people. Madame Pernelle, for instance, doesn't have many kind words for Elmire:
[Y]our behavior is extremely bad,
And a poor example for these children, too.
Their dear, dead mother did far better than you.
You're much too free with money, and I'm distressed
To see you so elaborately dressed. (1.1.13)
Now, who knows, maybe Elmire does spend her money a bit too freely, and maybe she does dress rather elaborately. Of course, Madam Pernelle isn't really a reliable source of information, and there's absolutely no other evidence in the play of Elmire setting a bad example or anything.
Elmire shows us just what kind of woman she really is in one crucial moment. When Tartuffe tries to turn the charm on and tempt her, she acts completely rationally, and keeps the best interests of her family in mind. It all boils down to a single response:
Some women might do otherwise, perhaps,
But I shall be discreet about your lapse;
I'll tell my husband nothing of what's occurred
If, in return, you'll give your solemn word
To advocate as forcefully as you can
The marriage of Valère and Mariane,
Renouncing all desire to dispossess
Another of his rightful happiness, (3.3.32)
Elmire is willing to compromise, to do things that aren't necessarily Just with a capital J, in order to protect her family. You could say that she believes that the ends justify the means. She doesn't care what "some women" might do. She isn't obsessed with defaming Tartuffe; she just wants to clean up the mess. As we see later, she's even willing to hide her husband under the table and flirt shamelessly to get what she needs. She puts herself in harm's way to save the day – Tartuffe is practically slobbering all over her when she finally ends the charade. That may not be conventional. That may not be "ladylike." But it's sure as heck effective and bold and courageous. What more could you want in a person?