Yeah I've had the porn site pop up once on mobile - but the SFW ads are extremely annoying....
I'd say ~ 1 out of every 4-6 pages I get a pop up or redirect that takes me to a completely different site; I then try to click back and it brings me back 2 pages instead of 1.
I used to randomly get adds that would open the google play store for some stupid game including but not limited to candy crush.