The two are seen leaving the Chateau Marmont hotel in West Hollywood. I'm sure if it was a booty call they could do it at their own homes so it's probably just dinner. And given that the paps regularly hang out at the establishment it was meant for us to see, don't kid yourself thinking they didn't welcome the intrusion.
He used to have a bit of a reputation for dating the ladies (think Jessica Simpson, Jennifer Aniston, Minka Kelly and Jennifer Love Hewitt) to be in the spotlight. And of course then there is his big pie hole that formed the words 'sexual napalm' in relation to Simpson. However, he claims to have grown up since that ridiculous Playboy interview that had him coming off looking like a complete douche.
Is he using, Katy? Is he using her? Who knows. Who cares, really, but they do have our attention don't they?