Kate's a skanky ho?

Why Kate is a whore.

Obviously I don't think that, but apparently a lot of disgruntled Bubbleheads do. So let's look at why.
Apparently it demeans her to have sex with Sawyer. If she loves him, or if she just has an itch to scratch, what's the big? It's been two months, they are consenting adults. It's not like she's been frakking every guy on the island so...why is it so bad to have really hot, no holds barred cage sex with a guy a lot of people think Kate loves?

Because it destroys their glossy image of Kate being the virginal bride to their noble Jack. So often Jaters try to ignore Kate's darker side, they want to pretend she's not a scheming hussy with good intentions. Much like Jack, actually. He doesn't really know her. He has an idealized image of her, and whenever that image is called into question he turns into a yelling abusive turd. He cannot accept that Kate is an extremely rough diamond in the rough. She's no angel. And she's no Mary Magdalene who's going to be spiritually uplifted into the plane of 'goodness' by the cleansing love of the virtuous yet exacting Jack.

Kate needs to find her own redemption. Not through Mr. Do as I say not as I do. She needs to stop looking for salvation in a father/authoritative figure and really look at herself and change what needs to be changed. But that doesn't mean cutting away all the dark. It's a part of her, yin and yang. She's not a whole person if she can't reconcile that part of herself and use it in a way that's constructive and progressive.

Kate ain't no saint. No amount of praying to the Island gods will change that.