You are most likely suffering from the Virtual Bagel (most recently named the Facebook Ads fraud).
I had noticed results like the ones you report before and never actually looked too much at it because I've never invested too much in FB Ads, until most recently after I did a campaign to increase the likes on one of my pages, the Followers grew and the engagement fell.
After searching, I found this great video resource from Veritasium:
The idea behind it is related with Click Farms and Spam clicks.
So click farms, explicitly forbidden by Facebook, exist and are very profitable by operating mainly in Countries like India, Pakistan, Egypt or Indonesia, where the workers are paid small bucks for 1000 clicks that are sold in websites for a lot more.
What happens is this workers build profiles that other than liking / clicking in the requested liked page, they like many, many others in order to don't look too spammy. They also try to behave like a normal user, clicking links, having interests and so on. The more likes they have, the most likely they broaden their interests and are able to catch your Ads.
This process is simple and quick: they click the ads and close the page. Over and over again. No interaction, no conversion, nothing. This behavior matches your reports.
One of other articles I found as this one at TNW, that basically concludes that:
These bots/spammers can make themselves more difficult to find by
continuing to diversify their likes and friends. That appears to be
the strategy here. Whatever the case, it’s a headache for page
moderators, who will have to spend more time gleaning the spam off
Luckily, there seems to be hope, as stated in the comments:
You can partly prevent this by going to your Page Settings and under
"Country Restrictions", add Thailand, India, Egypt, Pakistan, Russia,
Indonesia, Malaysia, the Philippines, and Mexico to the exclusions
list (topic permitting). Sadly, many worthless likes now come from
U.S. profiles too.
Facebook's marketing value is depreciating and I don't get why they
can't crack this ongoing issue that is dramatically affecting their
most valuable customers' ROI.
Of course in your case you're not buying likes to a page but traffic to a site and the users you're receiving, as I stated above, are just clicking things and liking stuff just to try to look real.
If you didn't target countries like India or Pakistan, the most likely scenario is that they are using proxies and setting up their addresses to US or UK in order to match the orders on the sites.
As immediate measures I would:
- Review the targeting settings on FB Ads;
- Implement your own tracking, sending the users to a script that can take the IP and save it to a DB in order to get the exact location;
- Try to create a campaign with the same settings but sending traffic to a page in order to see if the likes you gain, are from spammy users like the ones matching the articles I stated above.
For what I saw in the recent past, Facebook is not a good platform for paid advertising and is progressively losing it's value.