About some months ago the National University Commission (NUC), said that about 50 private universities currently in Nigeria are fake and not recognized by the government not to talk of being government approved. which means that all the students who suffered in a name of studying a course do that in vain, because His/Her certificate obtain from that institution is not valid for employment or anything.
Now some of those higher institution are still operating without the government going to close them down, maybe because some of them are owned by senior professors either overseas or here in Nigeria.
And most of this fake private universities are bible colleges which they claim to be affiliated to a university overseas.
What his your view about this.

and what instituted policies makes them fake ? or is it that they have refused to bribe the appropriate parties ?

No they are not approved neither recognized by the NUC.