Those things, I believe, have become bigger since Katy has become bigger. There is a certain dynamic in that, and I've read a reply thread to one of Miley Cyrus' tweets which was worse than anything I've seen in Katy's tweet threads even. So, she's not the only one, Miley, Selena etc, they all get it. Where articles and YouTube are concerned, they always prove with their 'arguments' that they don't know anything about Katy ('...at least X writes her own songs, at least X plays an instrument...') - Sometimes now I just state the true facts in my own comment, and flag a few as 'inappropriate' on YouTube, and on twitter I go through 5-10 depending on what I see which I report as spam - mainly because of what Katy said herself - 'out of sight, out of the mind'.
Katy is not the only one who can't always be perfect in imperfect TV setups, I've heard Lady Gaga struggling with those, too, and many others. So, that's not even something typical for Katy, but for everybody.
It isn't even Katy they're after, it's an outlet for them while being frustrated mainly over things in their own life. If somebody else was in Katy's place instead it would still be the same.
It isn't difficult to understand that it makes you angry, but remember that it doesn't matter a thing what people, generally just kids, say or think about her not knowing the simplest facts about her anyway.