Live TV? Ads. Shows available as part of streaming packages for channels included in live TV? Ads. Random other stuff "due to streaming rights"? Ads.
At this point I pretty much assume any non-Disney programming that isn't a Hulu original will have ads, and access it by other means, partly as a minor act of civil disobedience, but mostly because I'm impatient (i.e., never in my life have I actually watched television advertising, even when forced to sit through it).