Shimizu is a pretty good animator who doesn't do a lot of direction, so he's not incredibly experienced. Having said that though, I don't think the problem with the content of the episodes is entirely his fault. Some of the more divisive episodes of Dandy have been written by Keiko Nobumoto. She's a very, very talented writer who hasn't really worked much in like a decade. She wrote episode 8 (Lonely Pooch), episode 15 (River of Time), and episode 19 (Cloudian) so far. She's writing one more upcoming episode as well (22).
The way I see it, she been trying to cramp as many ideas as possible in each of her scripts for Dandy, but being someone who doesn't generally write comedy or short one-off random stuff, there's a struggle there to find the right tone. This struggle is compounded by the fact that her episodes all tend to be paired up with less experienced or talented directors who might find it hard bring out the best in the scripts into visual form.
I liked both ep8 and ep15 though, and I think I've talked about why I think they work and what they really bring to the series in terms of being unique episodes. Unfortunately I can't say the same for ep19. It just plain sucked for me. It was more annoying than funny, and a slog to get through. The ideas are interesting and would certainly have worked in a better framework but as it is, this story didn't work at all.
One of the interesting things to note about her episodes is that they all contain the theme of dualism. With her desire to pack as much as possible in each script, there really are two complete stories in each one. Episode 8 was both a What If story about finding Laika on some planet in deep space, alone and dying, and also a story about a dying mechanical planet held together by the last remaining inhabitants. The "connection" between the two stories being the joke that flea beings could be living on a dog. Episode 15 was about a lonely alien who collected smiles and had a creepy obsession with Dandy, but it was also about the River of Time, and what it would be like to see the Pororoca Phenomenon occur in it.
Episode 19 is clearly a story built around both the idea of a Cloudian and what it would mean to be one, while also trying to weave that concept around telling a story about both Scarlet and Honey and what they're like off-duty. I think if a much better director worked on this episode, it might have turned into a much better and more interesting character-centric piece. I don't know whose idea the laugh track was, but that really didn't help at all.
I'm pretty hopeful for Nobumoto's final upcoming episode though. It's storyboarded by Yoshitomo Yonetani, who is a real master at directing comedy. The episode director is Masato Miyoshi, who is pretty experienced unit director as well. The animation director is the most exciting thing about the episode though - Yoshimichi Kameda is finally going to make his mark on Dandy. Storywise from what I can tell from the title and the magazine synopsis, it's going to be about a once in a century epic drunken street dance celebration on Planet Grease inspired by the Awa Odori festival in Japan.