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.
Designated Hero: Excel does heroic things from time to time, but she is still working for an evil organization. Meanwhile, the City Defense Force (particularly Iwata) think they are working for the good of the city, but do as much harm as good.
It's more mixed up in the manga, where ACROSS doesn't really qualify as either good or evil organization (the world is definately just as corrupt as Il Palazzo declares, though he's hardly the best person to fix the matter), while the the civil servants really have no illusion about Dr. Kabapu's morals (or lack thereof), either.
Crosses the Line Twice: Episode 26 (titled "Going Too Far" and intentionally desgined to make use of this trope), as well as anything involving Shiouji.
Fridge Horror: When Ropponmatsu II starts acting rather intrusive towards Excel, we see Hyatt watching the two before the Relax-o-Vision starts. After that, we return to the same shot, with Hyatt sitting in the exact same position, apparently having watched as Excel lost "... a bunch of things".
Author's Saving Throw: Revealing that Dr. Shioji only likes to watch little girls because it gives him some sort of peace, instead of being a full blown pedophile, just as he was becoming more important to the main plot, was so this. The expanded explanation is that his mother left him with a skewed view on adult women, but was inspired by the innocence of his young cousin, now that she is grown he is simply trying to find that inspiring innocence elsewhwere.
Crack is Cheaper: With earlier volumes of the manga starting to go out of print, individual tankoban have been getting pretty pricey as of late.
Les Yay: Excel and Hyatt, obviously. Also, Elgala gets very touchy-feely with Excel when she's drunk, even though her "innermost thoughts" claims that she does not swing that way. Excel invariably retaliates with violence.