I've read he's a notoriously bad tipper and there are stories of him being incredibly arrogant and rude to service people. When he was young the title of his entourage was the p*ssy Posse which consisted of David Blaine, Harmony Korine, and Tobey Maguire and a medley of other B and C list actors who took the NYC late night scene by storm, destroying bars and clubs with their binge drinking antics and trying to sleep with as many women as they could.
And, he's now 38 and has just recently reformed the p*ssy Posse except this time it consists of Jonah Hill, Mel Gibson, and Bradley Cooper and he has pretty much sustained his nightmare streak into his older years with no signs of stopping.
Now, it's perfectly fine for Leo to bed as many women as he wants and chug as many bottles of bubbly that he desires, he's not the first celebrity to do so, it's just that he seems to do it in an overly crass way. The p*ssy Posse just comes off impossibly douchey and toolish.
That's all. I enjoy his movies etc. He's just a tool in real life, and I'm saying that with all the authority of a man who witnessed this through entertainment blog sites and articles in magazines.