These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Katamari on the Rocks definitely qualifies. It plays during the opening sequence and last level of the first game.
Ear Worm: Any of the songs that appear in the series, but especially "Katamari On The Rocks".
Ensemble Darkhorse: Out of all the cousins, Marny gets a lot of appearances in official art, wallpapers and the like. This is probably due in no small part to his simple, yet very distinctive shape; the obvious implications of which in this universe have been acknowledged, as seen here◊.
Other cousins, such as Dipp, Ichigo, June, Kuro, Miso and Velvet, are very popular. Many of these popular cousins appeared in the cut-down roster of Touch My Katamari, while others got references in the altered costumes some of them wore — such as Juno, June wearing a version of Kuro's Sentai garb.
Freud Was Right: Odeko's distinctive shape has spawned many a cheap joke at his expense. The fact that he's explicitly proud of his long head, and is prone to exaggerating its length, doesn't help.
Hilarious in Hindsight: The magazine Anime Insider had a section on Japanese video games, rating them on the basis that Japan should either "Export It" or "Keep It". One of the games reviewed as Katamari Damacy. It was given a "Keep It" rating, the reviewer considering the premise too strange for Western audiences, and doubted it would be well received.
Althought while it got an American release, it never got released in Europe for that exact reason.
Hype Backlash: When news that a Princess would debut in Beautiful Katamari came out, fans went nuts with anticipation: would the story introduce the Prince's new little sister? Or was she his girlfriend? Or the Queen as a child, to match rumors of the young King becoming playable? Even when it came out that she was going to be part of the Downloadable Content, fans still held out hope that this meant the DLC would have some real meat to it... But when she arrived to little fanfare or answers, people weren't happy. The fact she was linked to the disappointment about the DLC in general didn't help much, either.
It's the Same, Now It Sucks: Beautiful Katamari was hated by the critics for this reason. There was also a lack of variety in the tasks you got with few Special Rules levels, and 100% completion is impossible unless you buy the DLC. In fairness though, the actual game is the same goofy fun as ever so it's perfectly fine for anyone who's never experienced the madness before.
MST3K Mantra: You're rolling up living things (either one at a time, or in entire cities) and turning them into stars and stardust. You can even roll up the entire Earth itself. Yet they're alive and well and still on Earth if you retry the challenge. Indeed, sometimes the fans themselves ask you to roll them around, and they enjoy the experience and want to do it again (until you reach the top limit, at least.) The moral? Don't worry too much about these people and animals. The entire concept is more concerned with Rule of Funny than Fridge Logic.
Nightmare Fuel: The screams of trapped citizens as their workplace is rolled up into a gigantic ball of junk can be shudder-inducing.
And after the schenario ends, the king either transforms the clump into a planet or blows it up into stardust, people and all!
And the level in We ♥ Katamari where your Katamari is on fire and you have to roll up fuel for it. And there's nothing stopping you from accidentally rolling up that poor old lady, or maybe a cat...
The Campfire level does prevent you from rolling up people and animals (they "just" run away while engulfed in flames), but does let you roll up Second Cousin Kinoko. On the other hand, the level in BK and KF where you aim for heatdoes let you roll up hapless humans...
Katamari Forever's 'Last Chaotic Ambiance' music is this. Whhhhhy, why, oh why, oooohhh whyyyyyy *shudders*
Not to mention that other level in We ♥ Katamari where your Katamari is a sumo wrestler and you're rolling up food items for the sumo to eat and gain weight. There are no boundaries.
If you lose in the first game, you're taken to a screen where the King talks down to the Prince, saying what a disappointment he is, while a lightning storm and heavy rain take place. Every time lightning cracks, the King's figure is seen in various threatening positions.
The King's punishments get progressively worse with each new game. In We ♥ Katamari, his silhouette looms over you, completely black on a blackened screen, with the disappointed fan sitting on his shoulder, and he rapidly fires lasers from his eyes, which fill the screen and can't be dodged. In Me & My Katamari, he ties the Prince up like a punching bag and begins beating him senseless. In Beautiful Katamari, he puts the Prince onto his pool table, and begins firing billiards at him. Finally, in Katamari Forever, he rains meteors down from the sky while he sits upon his throne.
It's easy to think you nailed a level only to be told by the King that your katamari is barely acceptable. It is possible to get him to praise it, but it can be surprising how tough it is to do so, even for one who can get a passing grade with what seems to be a good amount of time left.
That One Level: "Ursa Major" and "Taurus" in the original game, and by extension, the COW♥BEAR level in the second. Anything related to bears/cows that you pick up finishes the level, and you want something large. However, it's easy to get anything from a "WARNING: BEARS" sign or a milk bottle to finish the game, and even easier to have a larger moving object knock you into small items.
The worst part about these levels is that, in most cases, when you grow beyond a certain point, the very smallest items disappear completely to save processor time. But this does not happen for these particular levels. It is very possible to grow so large that the milk cartons you tried to avoid early on become so small you can no longer see them. Ordinarily they would exist no longer, but not here. It is very possible to grow large in an attempt to get the biggest cow, then run into a milk carton that is so small it now occupies a single pixel.
At least the second game allows you to immediately restart the level, without having to listen to the King berate you for the small item like he did in the first. (The same cannot be said for the COW♥BEAR level in Katamari Forever, unfortunately.)
The COW♥BEAR level gets kicked Up to Eleven in Katamari Forever 's Drive Mode, to the point even the King himself questions your sanity when you begin the mode.
And at least picking up a tiny item passes the level; the same can't be said for the hot-cold level in Beautiful Katamari and Katamari Forever. You'll never look at a fire extinguisher the same way again.
For those who wonder, one level requires you to pick up hot stuff (hot meal, camp fire etc.) to accumulate 10000 degrees. The problem is picking up something cold (like an ice cream) your temperature drops immensely. And the cold items fell out from nowhere, usually directly on your path. And the bystanders will kick you into them. Oh, if you were thinking "take your time and plan out your path", your temperature is also constantly dropping (the higher it is, the faster it drops). Good luck.
Katamari Forever makes that level even worse, as everything is now in black and white, making it harder to pick out which objects are hot or cold. Oh, and the Broken Heart power ups become traps as they will draw everything towards you, including the cold items, and probably cause an instant game over. Have fun!
To make matters worse for those who are planning 100% Completion, several items (such as the infamous Cowbear) can only be found on these levels. As a few of these items are really quite large (again, such as the Cowbear), they are not easily obtained.
For an example not related to cows, bears, or temperature, "Make a Star 4" from the first game. You have ten minutes to go from five centimeters to a meter. Given the item distribution, that's not enough time.
Viewer Gender Confusion: Figuring out some of the cousins' gender can be difficult, especially without reading the King's profiles. This definitely isn't helped by the fact all the cousins can equip all the Presents, including ones that one would normally associate with only one gender.
The sparkly cousin Dipp is particularly prone to this, for some reason.
Woolseyism: Believe it or not, the ridiculous dialogue is completely intentional (and in some cases, an accurate and direct translation of the idiosyncratic diction used in the original game).
Writer Revolt: Keita Takahashi, the series creator, didn't want to continue the series after the first game, but Namco had other ideas. Considering We ♥ Katamari, the only other Katamari game he was involved and the direct sequel to Katamari Damacy, revolved on the King and Prince directly taking request from fans to pander to the fans, one could possibly interoperate it as this trope.