Yeah, you're better off buying a quality cigarette lighter to USB power adapter if you want to charge a phone. Try to stick w/reputable brands as I wouldn't be surprised if crappy brands could put out dirty power.
Although these aren't cigarette lighter units, the below can illustrate the difference between quality vs. garbage.
https://www.righto.com/2012/10/a-dozen-usb-chargers-in-lab-apple-is.html
http://www.righto.com/2012/05/apple-iphone-charger-teardown-quality.html
http://www.righto.com/2014/05/a-look-inside-ipad-chargers-pricey.html
One would hope that a large company would have/can hire some decent EEs and has good processes in place vs. a no-name where what you get could be very YMMV.