Some brands do it occasionally and others do it all the time. It's always been an easy way to generate awareness for a brand if you create something that is a bit contentious and likely to cause controversy in the public eye. The short-term gains can be great but more often than not there’s severe backlash that does more harm than good.
You should always carefully consider if it’s worth it. Maybe your brand could pull it off but in my opinion if you’re going to do it, do it well. Don’t just court controversy for the sake of it, rather go flat out, balls to the wall and just do it. If you do it well, and your brand gains a reputation for it, things will work out fine. But if it doesn’t, be prepared for the consequences. Don’t let your ad agency talk you into something that you’re not comfortable with. They wont be the ones getting lynched when things go pear-shaped. They’ve got plenty of other clients and they’re far out of the public eye to really worry about it (and more often than not, it’s better for them if things don’t work out).
So with this in mind here’s a selection of controversial ads for your viewing pleasure.