What exactly is a rogue antivirus? I'm utterly curious?

A Rogue is a virus that poses as a legitimate Anti-Virus program used to steal your credit card info, and is mainly dropped by Trojan viruses previously installed on your machine.

There are several ways a Rogue could get on your machine, mainly through redirect sites that take you to a fake scanner page, one Rogue that has used this technique in the past is Security Tool. Another way a Rogue could get on your machine is through browser exploits or posing as a legit AV such as AVG.

As for removal, most Rogues tend to block Task Manager, so you would need to download a tool called Rkill, which terminates any processes running in the event the Rogue tries to hinder the removal process. Another way to remove a Rogue is by simply using an activation key, previously cracked by someone else. But the one way to completely remove a Rogue is by using MalwareBytes AntiMalware, or ComboFix.(It is recommended that you use MBAM first, because Combofix is a very powerful tool.)

A "rogue antivirus" is a program that claims to be an anti-virus but really isn't. Instead, it's malware itself, pretending to scan your machine but really trying to sell you "protection" and/or get your credit card number and/or install more malevolent true malware on your machine.

Linguistically, though, since it's not really an anti-virus, it can't well be a "rogue" one.

Hope that helps.

It's a malware program, usually or the trojan type, disguised as a genuine antivirus program.  Its main function is to extract money from you, and plant more spyware or trojans on your computer.