I mean... the channels that have thumbnails like that usually are intended for a Kid Audience (or at least targeted at bringing in children, even if the content isn't something a child should watch), because that's what gets you the most cash on that Platform.
On YouTube, ClickBaity images and titles like "You‘ll never believe this..." tend to be dead giveaways for content I don't care to see. Webcomics? Less reliable. I've seen some erotic click-baity banners for good, entirely PG webcomics like Gaia (SandraAndWoo/Gaia).