It was a cross between Alf and Charles In Charge. Start crying now. But allow me to expand on that description. Meego starred Perfect Stranger's Bronson Pinchot as Meego, a nanny who was really a space alien with magical powers watching over a family of kids that included Jerry Maguire's Jonathan Lipnicki.
If you are a fan of Meego and I have grossly offended you I am very sor... oh heck I can say it. I'm NOT sorry. IT WAS MEEGO FOOL!!!
By this point, Miller-Boyett had actually changed its name to Miller-Boyett-Warren, having absorbed half of the Bill Bickley/Michael Warren team that wrote and produced most of its shows. (Bill Bickley, apparently sensing that the bottom was about to fall out of the cheesy family comedy market, had retired.) CBS picked up the M-B shows that ABC had dropped, plus this new one, and tried to go head to head with TGIF.
I remember at the time I was still watching Sabrina (in its second season) and would sometimes check out the other supernatural comedies ABC ordered in a desperate attempt to cash in on the success of Sabrina, Al Jean and Mike Reiss's Teen Angel and Michael Jacobs' You Wish, but I never watched a moment of Meego, presumably because I wasn't watching Family Matters either.
Anyway, Meego was clearly a CBS attempt to pull a Sabrina by doing a supernatural comedy of their own, and M-B did their usual thing, borrowing heavily from previous shows they'd been involved with (Mork and Mindy, Perfect Strangers). As always, they put together a decent supporting cast (including Michelle Trachtenberg, available after the cancellation of The Adventures of Pete & Pete). But the title sequence is terrible, and the theme song kind of sounds like a Mork knockoff too.
I phrased the subject heading as a question because, having never seen a full episode of this series, I have no idea if it really was the worst show of its era. It seems like a good candidate, though, based on the few clips I've seen. One clip appears to be from an episode where the teenage boy uses some kind of alien gizmo to force a girl to like him. And then the Valuable Lesson is that people should like you for who you are, whereas the Valuable Lesson should be that this character is basically a rapist.
I'm so disgusted by that clip that I will stop there. So I have no desire to see more of this to find out if it's truly the worst show of the '90s, but at the very least, I think it's clearly worse than You Wish or Teen Angel or any of the other Sabrina ripoffs.