I had success with Facebook with Pokemon Go, I don't believe it's easy reproducible on a lot of other things. I wrote everything down here : https://news.ycombinator.com/item?id=12858993

Tldr; don't do Facebook ads if your not doing a hype and if don't want to give things away for free

If you only want useless likes locked in on Facebook, you should do go all on. Remember, you can't easy notify the people who liked your page even though you payed for them