Much of our understanding of the Wife of Bath's character comes from what she tells us about herself. Of course, we have to take these statements with a grain of salt, not only because we suspect the Wife may have ulterior motives for portraying herself in a particular way, but also because some of the things the Wife tells us about herself are contradictory. However, we can be reasonably sure that, as she says, "I am al Venerien / in felynge" (615-616) – that she really enjoys life's pleasures, particularly sex – not only because she repeats versions of this assertion constantly throughout her Prologue, but also because Chaucer has hinted at a similar characterization in the General Prologue. He also confirmed there that she was, as she describes herself, "Marcien" – possessing a "sturdy hardynesse" (617), which in her old age has manifested itself as a large stature.
It matters enormously to her characterization that the Wife of Bath is a woman, because throughout the Prologue she parrots numerous antifeminist stereotypes of women and implies that she agrees with them, offering herself as proof. For example, she says that "Half so boldely kan ther no man / Swere and lyen, as a womman kan" (233-234) in the context of describing how she lied to her husbands. She also claims that "Deceite, wepyng, spynnyng, God hath yive / To wommen kyndely whil they may lyve" (407-408) in a similar context. Can we conclude from this coincidence of stereotype and character that the Wife refers to other antifeminist stereotypes? Well, the proof is in the pudding: antifeminism stereotypes women as lustful. Check. Manipulative. Yep, definitely. Long-winded chatterboxes. Um, her Prologue is a meandering 862 lines, longer than many of the tales, so, yeah. From all these corroborations we're probably safe to conclude that the Wife is for the most part meant to be a personification of antifeminist stereotypes as much as (some say more than) a three-dimensional character. So if we want to know about the Wife's character, we can ask what medieval antifeminism has to say about Type of Being: woman.
Most of the Wife of Bath's actions serve to confirm things she's told us about herself. She says she's all Venerien, taking great pleasure in sex and the finer things in life. So, when we witness her genuine delight in the idea of Solomon's hundreds of wedding nights, or her joy at remembering the pleasures of her youth, we regard this as confirmation of her self-characterization. The Wife claims women are deceitful; witness her account of how she deceived her first three husbands into thinking they had insulted her in their drunkenness, or how she convinced #4 she was having an affair. When we learn how the Wife withheld sex from her husbands in order to gain control of property, or how she chose her husbands for their wealth, we learn that she's strategic (the positive spin) or manipulative in her dealings with men and regarding sex. This is an example of how the Wife's account of her actions trumps a self-characterization (the one about how she'd sleep with anybody without regard to class). From her fairly competent defense of marriage, we learn that the Wife is rhetorically strategic, as well.
But some of the Wife's actions surprise us and tell us things she might never admit about herself. For example, she yielded control of her property to Husband #5, who, perhaps not coincidentally, was also the one she loved the best. And when this same husband forced her to listen to horribly derogatory stories and proverbs, she felt real pain. These last few actions reveal that, despite her show of worldliness and a mercenary approach to men, the Wife is just as susceptible to love as the next person, and just as liable to be hurt by wounding words from a loved one.