I actually quite like Steven Universe, but that's probably because I sit through so much awful, awful shit that anything that has even a semblance of effort put into it seems good by comparison. Shows made for the preschool demographic are almost always barrel-scraping shitology.
* Blaze and the Monster Machines
I'll give it points for trying to teach kids about science in their own cack-handed way, but there's something so off about it all. Why are there only two humans left in this world of sentient cars? Why is one of them the main car's driver when it's been proven he can move on his own? Why is Crusher so obsessed with winning races when he can build giant world-conquering robots? Why does the channel I have to watch this dreck on insist on repeating the same episodes several times a week?
* The Mickey Mouse Clubhouse
Mickey's voice is beyond shrill, the female characters do nothing but stand around going 'Oh my!' from time to time, the camera keeps zooming and swinging around enough to make you seasick, the hot dog dance is a cacaphonic nightmare and it's a completely shameless cash grab even by Disney standards.
* Roly-Poly-Oly
Hideous, hideous design, weird 1950's nostalgia that would fly over the head of any toddler, unfinished rendering all over the place, horrible 'cutesy' voice acting and inconsistent world building.
* Horrid Henry
The animation and voice acting is actually pretty good, the stories are the usual crap but I'm mostly putting it on this list because every kid I've ever worked with has behaved worse after watching it. Henry's parents are ineffectual liberal wankbadgers.
* Thomas the Tank Engine
Not the old episodes, they were quite interesting, there were explosions sometimes and Ringo Starr's soothing voice. The newer episodes have stripped it all back so it talks down to kids and tosses out any semblance of a story for blithering idiocy. Also, an island the size of Sodor does not need a railway network of 69 trains unless the Fat Controller is running a massive drugs and money laundering empire (he probably is.)
* Bubble Guppies
Why would they set it underwater if they're just going to ignore the setting all the time? At least when Spongebob does it they take the time to break the fourth wall. The characters are indistinguishable from each other except for that one kid with the goggles who doesn't smile, and even he's boring.
* Kipper
I find its anti-cat bias offensive. And it's boring as hell.
* Dora the Explorer
I know it gets a lot of praise for being interactive, but it is painful to sit through. Nothing happens. The movie is over an hour of things not happening. The new spin-off is slightly older girls still doing nothing.
* Team Umizoomi
Ugly, and so boring I have nothing else to say about it. I think I've blanked out the hours of having to watch this with a sick child who wouldn't watch anything else.
* Sally Bollywood
It looks, sounds and is written as if by someone held at gunpoint.
I would put Barney, Boobah and that weird one about the apes who were in a band on the list but they're not animated. Waybuloo is half-animated and is boring, faux-zen crap.
If/when you have kids, watch their favourite shows with them. Otherwise you don't know what kind of crap the networks are trying to shovel into their heads.