I don't think it signifies any of those things. This is all new stuff. Some people have decided to offload image-creation to machines because what they care about is the text.
This stuff you say it signifies, it says more about you than them.
If it looks like cheap generic crap it’s probably cheap generic crap. Most AI imagery looks like cheap generic crap.
It’s flooded the market to the point average users are starting to turn away. Look different or be relegated to obscurity.
Yeah, everyone knows the best content is on a professor’s site from the 90’s, with no images. Maybe some figures, but if so, they should look like they were printed, physically cut out, and then scanned. Bonus points if the background of the image absolutely does not match the color of the webpage.
So now we have this low-effort image generation tool. At least it doesn’t indicate that the author wasted a substantial amount of time looking at pictures. Still a silly waste of time, but at least it is a small one.
It's about experience visiting many sites and spotting a correlation. There is a very bottom of slop, the equivalent of the chumbox from earlier. But on the higher end it may be more like you say. If there are other indicators of quality, I wouldn't penalize it for AI use. It's like having lots of piercings and torn clothes and tattoos. You may be a genius scholar who is kinda into this as a hobby or you may be an actual lowlife who can't hold down a job and gets into trouble with the law all the time.
People will always make snap judgments, you can't inspect every website in detail. So if you use AI, make sure there are some other signals of quality.
Some use of hero images by bloggers is a deliberate style choice, to emulate the norms of professional journalism.
A lot of traditional news outlets have a style rule that every article must have an image. Look at https://www.bbc.co.uk/news https://www.nytimes.com/ https://www.economist.com etc - every article has an image. Even a report on something highly abstract - "BP reports record profits" - will be illustrated with a photograph of some BP-branded fuel pumps. Stories on things like cybersecurity and inflation get generic images like snippets of blurry computer code, banknotes etc.
Some bloggers feel their blog is improved by adopting the style of professional journalism, and (among other things) put an image on every article. Even if for a programming blog good lead images are hard to come by.
Interestingly, professional journalism organisations often have pretty strict codes of practice about images, and photoshop use. They have rules on everything from illustrating one rocket launch with a photo of another to posing the subjects to colour-correcting images to creating multi-image collages. So I don't imagine we'll see many AI-generated images in traditional news outlets any time soon.