I bought a Sony smart TV about a year ago. I don't get ads per say, but there is a prominent area in the main menu where Sony wants to shill their services and that can't be turned off. Also, TV has to be restarted every week or two (it's android).
On the other hand, I love that I can easily cast screen from my laptop or photos from phone using built in chromecast.
Smart TVs are a mixed bag.