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.
Demonic Spiders - You are guaranteed to hear the phrase "FUCKING NINJA BALLISTAS" at least once per High- or Max- security Player Versus Environment mission. Bonus points for actually being robotic spiders.
A Ninja Minion Ballista is, as the name implies, a mobile artillery platform. One armed with powerful, salvo-firing grenade launchers. Now, there would be nothing special about them, but unfortunately an AI glitch in early development stages changed the Ballista's modus operandi from "upon spotting an enemy, flee to a safe distance and provide covering fire" to "upon spotting an enemy, approach and shotgun a grenade salvo in their face". It proved to be way too efficient to fix.
Now where they obtained their improbable stealth skills is a complete mystery. They often spawn, say, under stairways. Or maybe even on the ceiling. Somewhere in a corner along the main mission path. The one corner you probably wouldn't know existed if they didn't ambush you from there once.
Alarm responders are special androids that spawn from tripping various alarm raising events in Player Versus Environment missions, support scanners or come randomly when fighting a boss. A single one is not too much of a concern. The problem is, they spawn in two groups of 6-8 near the players. They also have a nasty habit of firing their weapons at the same time, usually at one specific target. Anything less than a tank assault with a ranged shield is vaporized from the amount of concentrated Dakka they release.
The way they look with their helmets and shoulder pads, there's a reason they're nicknamed "football teams". The way they appear out of nowhere and try to overrun you with Zerg Rush and More Dakka is scary.
Ballistas have a very close cousin in the Minion Sentinel. Instead of moving in and volleying grenades, they hang back and salvo swarms of rockets across the room. The rockets are fairly slow-moving, but they deal massive damage there are often several sentinels in a room at one time. Ballistas and Sentinels are almost always in the same groups together, meaning explosions are pretty much everywhere. It gets worse, as in Ultra-Max Security all of the standard Minion Androids are replaced with nothing but Sentinels and Ballistas. A lot of missions will end in a Macross Missile Massacre.
And then we have even more spidery spiders, Support Widows. The tricky thing with these bastards is that they have a frikkin' Tractor Beam, with which they haul a targeted group member right into their arms, where they then commence with the punching. What makes this worse is that they're almost never alone... Oh no, count on them grabbing your Medic, hauling him out from cover and giggling gleefully while the Minion Ballistas, Sentinels and other murderous mecha rip him to shreds. Bonus points if they come at you in groups, since they then often chain-pull some poor sod into oblivion.
8.8 - One of the usual offenders, Gamespot, did it, giving the game an insultingly low score of 5.0. The fans complained, so Gamespot took the review down... Only to post a new one later with the same score. Pasting and ridiculing professional reviews of the game is now one of the fandom's traditional pasttimes.
Game Breaker: The Bionics offhand. There's a good reason why Team Fortress 2 made the Spy and Scout into separate classes. The result is something resembling Modern Warfare's infamous "marathon/lightweight/commando" loadout, if the commando perk let players turn invisible at will.
Goddamned Bats - Elite Assassins. Their AI is notorious among community for very accurately capturing behavioural patterns of any non-sniping recon player.
The most common Minion Androids are also alarmingly accurate and deadly with their would-be peashooters.
Colony Spiders/Support Widows in Player Versus Environment missions. They on their own are not too dangerous, they just have a lot of health and at medium or closer range their guns can be deadly. What makes them so despised is that they have a beam that pulls you to them. They do nothing else but pull you closer where they will melee you if you stay nearby. Not dangerous by itself, but they seem always do it when there are a dozen other mobs around to reduce even a prepared tank into plasma singed goo.
Oh and they also like to pull you into scanners for some demented reason, thus causing the Fottball team to kill you and you have no choice but to die.
Elite Techros like to build buff stations that reduce the damage buffed enemies around it takes. In addition, many have a little drone that locks onto a person and just opens up on them endlessly until it or the target are destroyed, and the techro will constantly spawn one from itself as long as it is alive. Add on top of all that wonderful fun, they use a grenade launcher that knocks those hurt by it around like a kid jumping into a ball pit. With an uncanny aim and timing, it is common to be knocked out of cover just in time to eat full salvos of missiles and grenades from mobs.
Elite Alchemists are the medic variant to their brotherly Elite Assassins, Helots and Techros. On their own, they are not terribly dangerous, possessing only a simple mook rifle. What makes them dangerous is a souped up copy of the medic Regeneration ability, which is guaranteed to keep them alive until it expires, a nasty aoe heal that'll bring anything short of minibosses to full health, and a weak damage-over-time aoe poison that makes the victim take more damage. And they normally spawn either in packs with other Elites to support them.
Magnificent Bastard: Avatar has definitely earned this as his planning creates the Commonwealth and gets himself elected President and then plans to be forced out of office so that he can introduce the changes to humanity he wants and at the same time ensure that AI research is stopped permanently to eliminate any possible threats to his power.
That One Boss - The Vanguard. Seeing it on the other side of the boss room doors is something of a "Oh, fuck me" moment for the more experienced Ultra Max players. The boss itself is actually not a huge problem. However, it's rather infamous for its very horrifying habit of calling in multiple swarms of responder units, due to some kind of glitch which has yet to be addressed. One minute you're dps'ing the boss and the next you suddenly have 30 alarm responders, 4 maintenence droids (which heal the boss), a squad of techros (which heal the boss faster), and a bunch of assassins that you can't even see at first. Additionally, Vanguard has a whip-like grab attack that it will lash out with, grabbing an unfortunate victim and reeling them in extremely quickly for a melee attack.
In addition, Think-Tank is sometimes this for similar reasons, though this results more from inexperience in how to approach her. The ThinkTank will put up a protective barrier that makes her immune to damage until the shield is broken. When the shield goes up, she calls in random responder units. Thing is, after she takes a certain amount of damage, she will put the shield back up again and call more responders, every single time. Inexperienced players will often keep shooting her instead of kill the responders, meaning that quickly the room will be filled with, not just regular responders, but whole squadrons of minibosses.
Dune commander. Not only is he constantly reinforced by angry, angry mobs of Goddamn Bats, but his missile barrage can gib almost anyone short of an Assault Tank. His AoE kills anyone and anything within its radius, no exceptions. Most raids fail due to its inability to keep dps up on the Commander and the mobs, and robos aren't able to repair the core through the damage.
The Switchblade. It's a Melee Berserker boss that chases a random player around the area, and periodically summons a Vortex that sucks everyone towards it and damages them. The Vortex has a fairly large range, and is capable of wiping out the entire party, or crippling them for the Support Teams to finish off. You can avoid it with the Jetpack (like all Grapple attacks), but odds are you won't have enough energy by the end to deal with the Swarms of Grunts or the next Vortex attack.
The Viking. Unlike everyone else on this list the viking doesn't have a really fancy trick, it makes do with two rapid fire autocannons which are ok and flaming rocket spam. did we mention the rockets can kill people in a few seconds and just happen to set you on fire? Oh and it gets better these guys also happen to choose when to go "screw it rocket spam time" seemingly randomly. Thats right, the guy just happens to pick when to turn this fight from "same old same old" to "respawn time" whenever it wants.
The Magmalance is a powerful rocket launcher available for Assault agents that deals massive damage and ignites enemies it hits, dealing further damage. Said massive damage and ignition also apply to the Assault using it, leading most to shy away from close quarters combat. Namely on control points. Naturally, the rest of the team frowns upon such behavior, as it's usually the Assaults who are expected to stand on the point.
This actually applies to any explosive weapon in the game, Magmalance just gets most of the mouthfoaming because it's the best and thus most commonly use rocket launcher for Assaults.
The irony is that none of the complainers can make the connection between them not wanting to play medics and assaults not wanting to play tanks.
Robotics' Lockdown Drone. Pops up for around ten seconds, picks a target, heavily damages and ensnares it. Pretty much a guaranteed kill on anything other than Tank-spec Assaults.
Poison medics. If you have enough of them on a 10-man team they can cut the enemy team's damage resistance by half and choke off 95% of all healing sources when partnered with a Scorpia Recon. There aren't enough healing waves or healing grenades to counter that much poison. Combined with the fact that ranged resistance is the most prevalent resistance to stack, pretty much every Assault in AvA will not be running aoe shield, and competetive teams almost never have more than one Robo (their mechs are immune to poison), running a team of poison medics is considered extremely cheap. By themselves, however, poison medics are simply extremely annoying and often make the rest of the team mad when they won't heal.
Add to all that the fact that the poison medics' main tools, Neutralize Wave and Poison Aura, are point-blank aoe abilities that do not need to be aimed, and you get a very ugly ball of distilled hatred rolling around the community.
The entire Recon class. Being the second most popular and numerous class in a game that only requires one or two of them on a team doesn't help. Whether you're the "high tier" type, who locks the entire enemy team down, or the "low tier" type, who spends most of his time trying to murder some useless chap miles away from the point, depends on you.
They Changed It, Now It Sucks - Many players' reaction to the 1.3 "Sandstorm" update before it was released. Everyone seems rather pleased with it now, however.
There are mixed reactions as to the 1.4 "Free Agent" update. So, only partially subverted.
The reaction in city chat to the new Burning Fashion store introduced in patch 1.44 has been... Somewhat mixed.