This sounds more like an issue with your ad targetting than with Facebook.
First step: only target users in countries that you care about and (sadly) do not target Indonesia, India, Pakistan or anywhere in Africa as these are mostly where the fake profiles are.
I disagree that any specific advice will help an individual marketer...I think the biggest issue is that the economics of acquisition on social (factoring in internet marketing budgets and customer LTV) doesn't work well for brands that aren't already operating at significant scale. Otherwise, Teespring would be a billion dollar company by now ;)
My guess is that social marketing works ok for brands that have a strong competitive position AND healthy margins.
Healthy margins and product appeal moreso than competitive position.
Teesprings product offering is far too broad to benefit specific targeting which really just leads to low user intent, which leads to huge acquisition costs. No one gets excited for tshirts.
Products outside of these hugely saturated markets do amazingly well if you know what you're doing.
Did you watch the video that the parent shared? From the sounds of it, targeting didn't seem to help at all. The video stated that they seem to think that clickfarmers will like -anything- so that a sudden surge of likes from a specific region on a specific page seems less fishy.
First step: only target users in countries that you care about and (sadly) do not target Indonesia, India, Pakistan or anywhere in Africa as these are mostly where the fake profiles are.