Why basic demographic info are unknown on Display Ads report?
I've been running Adwords for both search ads and display ads and know display ads has demographics report, basically by gender and age range. The report offer you insights so you may have idea what's your best audience and how can you optimise it over time with the demographics targeting as well.
I'm not sure how Google tell demographic info but in my cases, I found most of the audience of my campaign are unknown. The business we do is staffing and recruiting, so the people who interested in our ads are looking for a job. Over 90% user clicks are unknown for both genders and age, which doesn't help at all. I would like to know why this happens? Is it a technically issue that can be solved by my campaign setting, or is it just as common as everyone else?
FYI I'm located in China and have VPN managing my account.
Re: Why basic demographic info are unknown on Display Ads report?
Google doesn't know demographics of all the users and also most websites don't have demographic info of their customers. In addition to this, not all websites opt in to show demographics of their customers. Hence, you might see traffic coming from "unknown" demographics. If you don't want to show them your ad then you can exclude that category from your campaign and target other demographics for better understanding of your perfromance. But as you said your major chunk of traffic is coming from the unknown category, i wouldn't recommend that.
Hope this helps.