I'm never sure whether I can take anything Katy says at face value. She has such a snarky and sarcastic personality that is genuinely funny at times, but I think her delivery is frequently off and consequently a lot of people misinterpret what she says. At least, I hope they're misinterpreting, cause otherwise she's just a huge bitch.
I think the tone she sometimes adopts for a witty little jab or sarcastic comment seems more vicious than she really intended. But also, she makes the mistake of attempting humor and sarcasm through Twitter, and we all know how well sarcasm translates online*, particularly if you are a celebrity and there are people who are eager to make a story out of everything you say.
*It does not translate.