I only clicked on Rihanna's Pour It On once because it was the next one on Katy's iTunes playlist. I suffered from anxiety symptoms, insomnia and loss of appetite for days afterwards. Britney's video I've never seen, I'd be too scared of it.
The way I understand it, why would Katy have to make an effort for a sexy video? - She only needs to be on the screen at all: job done.