Op what's the source of such fb pages likes? I hope it's not from so many likes4likes site where you may have accumulated points and will use them to send us likes.
25% of likes will come from likes4likes sites. The other 75% i am afraid that i can not tell you.
If you cannot tell the source then it is sure that you have a service of providing fake likes but don't worry because there are a number of people who need only likes no matter it is from real human or from fake systems because they only want to show their business as a bigger company having bigger social media community.