It's stereotyping. I don't mind ads if they are pertinent, but if you look at the choices of catagories, anything I want doesn't exist. Fashion doesn't interest me, unless it's finding patterns and fabric for what I want (never advertised). I don't buy ready made for a lot of items. Except for stuff being easy to clean, I don't care about style. That leaves out half of the sales ads right there.
The other is dealer exclusives. If you want a camera, you might see ads from various companies that sell cameras. But all of said companies use the same ad whether it be put out by Canon, Nikon, Pentax. The ads never give total specs, either. They won't give price (fair trade) but specs? Those ads are useless. You have to hunt on the net to find the specs.
Hobbies aren't broken up. That's where the biggest demographic info is way off. Men are taking up quilting and machine embroidery. It may sound funny, but both are computerized. Programming X,Y coordinates appeals to some. (I can digitize) If you program, you have to test. A lot of women and other men think these guys are weird. Therefore, most ads and magazines are geared to women. If the men don't care for this, I don't blame them. I'm not interested in kirke, kinde, kuche, either.
You can blame telephone and mall surveys. We ignore them. I've had some get outraged since I didn't give what they considered the "right" answers. The spammers are getting too pesty and a lot say they are a survey when they are selling. You see references to why people aren't being loyal to a certain product. Never the reason that maybe current product is buggy and so bad no one wants it.
Scraping likes from most social sites would probably be more accurate. Even getting info from current inventories of merchants would be more pertinent. The merchants usually know where their clientele is coming from.
There's been too much of this, and demands for more, more more. How about some way to make things more pertinent? And use quality not quantity.