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.
Dork Age - Champions New Millenium which featured a new system (that players hated) and updated the setting to a Darker and Edgier 1990s Image-style universe. That the artists from R. Talsorian Games felt like copying Rob Liefeld art for their illustrations probably didn't help.
Fan Nickname: FREd for Fifth Rules Edition, and 5er, pronounced fiver, for Fifth Edition Revised. FREd is a backronym; it was originally adopted by members of the discussion boards from a comment made by Steve Long the he "...didn't care if they called it [the fifth edition] Fred..." as long as they bought it. Thus it was affectionately dubbed Fred, and only later turned into an acronym.
The fourth edition rulebook was commonly known as the BBB, for Big Blue Book (the main color used in the cover art). A fan discussion that started when everyone realized that Big Black Book (the main color on the 5E cover) would have the same initials is what led to FREd.
Fashion-Victim Villain - Many bad, bad costumes have appeared over the years. Particularly noteworthy is Power Crusher - "As Power Crusher, he wears a jet-black hood. His tunic is orange above, dark blue below with a purple stripe charged with a red gauntlet. His actual gauntlets are also red and crackle with yellow power. He wears brown trunks and boots, and light brown pants with white side stripes". Yow.
Fridge Logic: According to the rules of the universe from 5E onward, superpowers and the kind of tech that only exists in comic book universes is only feasible if the amount of ambient magic in the universe is high enough to bend the rules of physics. If some cosmic event causes that amount to go down, then reality will start behaving realistically. Superpowers won't be possible and implausible technology will indeed be implausible. But immortals will stay immortal.
Running the Asylum - A rare positive example; a number of the current writers used to be Champions players.
A number of the NPC heroes that have appeared in the RPG were based on player characters; Dr Silverback was Hero Games/DOJ owner Darren Watt's PC, the Harbinger of Justice was writer/owner Steve Long's.
To be more specific: In all editions prior to Sixth, characters had a set of "figured characteristics" whose base values were derived from the primary stats (Strength, Dexterity, Constitution, Intelligence, Body, Ego, and Presence). For example, the base value of your Endurance stat was 2x your Constitution. In 6th Edition, the formerly figured characteristics were made into primary stats in their own right, with base values dependent on nothing. This meant that a character with a high Constitution no longer automatically had more Endurance or more Stun-damage hit points. Worse, your Combat Value — which determines your chance to hit a target and your chance that an attacker will miss you, thereby making it the single most important stat in the game — used to be a figured characteristic based on Dexterity, so a more agile character automatically became both better at hitting things and harder to be hit. But no more. Now, your Offensive Combat Value and Defensive Combat Value have to be bought up separately, for a lot more points than you'd pay in previous editions just to raise your Dexterity by the same amount. Since you still need to be efficient in your point expenditure, this leads to super-accurate punching machines that can't dodge to save their lives, and lithe martial artists who can't hit the broad side of a barn.
Other major changes introduced in 6th Edition include:
The removal of the 1 inch = 2 meters game scale, so that the game is no longer geared toward the use of figures on a hexagonal map. (Ironically, the Hero Games logo still features a human silhouette inside a hexagon.)
The elimination of the Elemental Control power framework, which gave you a point-cost bonus for having a consistent "theme" for a set of powers.
A more flexible but also more complicated system for constructing Enhanced Senses.
The replacement of the Comeliness characteristic with a tiered set of Talents to represent good looks.
A sharp reduction in the number of points a character can gain from Disadvantages (now called Complications).
The introduction of Damage Negation, which reduces the number of dice an attacker rolls when determining damage against you. It also reduces the knockback inflicted, thereby making it more powerful point-for-point than straight defenses.
The previous change — from 4th Edition to 5th Edition — wasn't as extreme as the change from 5th to 6th Edition, but there are still 4th Edition purists out there who refuse to use the 5th Edition rules. Damage Shields, for example, became monstrously more expensive in 5th Edition, due to the need to buy the "Constant" advantage for nearly every power that the Damage Shield could use as a base.
This trope also applied pretty strongly to Champions: New Millennium, which used an entirely new system which combined elements of both Interlock (the system for Cyberpunk 2020 and Mekton Z) and the Hero System. Of course, C:NM did suck.
C:NM sucked so badly that Fuzion, the name of the system used, is now very much a derogatory term in the Hero System fandom.