When did Scooby Doo start to go downhill?

These 1st 2.5 seasons were great. Pretty much should’ve stopped then. Like Star Wars.

I can't remember exactly but like the other poster said it probably started when they introduced Scrappy Doo and then Scooby's other relative who for some reason reminds me of Cousin Eddie from National Lampoon's American Vacation movies

Whenever the monsters and ghosts became real instead of being sputtering guys in masks who would've gotten away with it if not for meddling kids and that mutt a theirs.

Scrappy don’t.

I actually like Scrappy more than most but he worked better in the mid 80s to late 80s without Velma or Fred present. Unlike others I didn't find him annoying in his debut show. I more just find him pointless when the entire gang is around. In 13 ghosts of Scooby Doo and the 3 Scooby Doo TV movies from the late 80s he gets to do more stuff.

I have always hated him being the bad guy in the 2002 movie. Also, I like Scooby Doo on Zombie Island, Scooby Doo and the Witch's Ghost, and Scooby Doo and the Alien Invaders. I also like the original Show and the 70s one that featured Scooby Dum.

But I can't blame them for wanting them to face actual Supernatural monsters instead of continuing the humans wearing costumes premise of the original show. But to each their own.

Scrappy Doo

After the 3rd episode in season 1, because it became very repetitive

To be honest, I'm sort of rewatching the show (mostly in the background) and I think it's already kind of gone downhill in the second season. The quality of the animation and voice acting seem lower and the new theme song is horrible. The chase songs are annoying and don't add anything either.