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.
YMMV: Dota 2
Acceptable Targets: The playerbase, like all MOBAs, have a seething hatred for all people Brazilian or Russian due to a Vocal Minority who troll games going "Huehuehue" or going onto the American servers and demanding them to speak Russian.
Base Breaker: Jakiro used to be a relatively mediocre nuker with a nice passive and pretty good at pushing, but overlooked among better options. Then his Ice Path was changed to be one of the best stuns in the game, while also dealing damage and being cheap in mana. Jakiro overnight went from rarely ever picked to a staple, and now draws cries of being a Game Breaker as well.
Dragon Knight gets some flack for having the longest Level 1 stun spell in the game. The trade off is that it's a melee range until level 6, but it can chain stun with something else like the above Jakiro and turn a tough lane into a complete massacre.
Invoker: One of the most powerful heroes in the game whose power justifies his high skill ceiling or an overcomplicated Jack of All Stats who all but requires you to either have outstanding muscle memory or have a flowchart in front of you?
And ever since his nerf after the second International, inferior to more focused supporters, nukers, etc and takes too long to set up or still a strong pickup, if more situational.
There's also the classic MOBA debate of whether there should be a surrender option. The closest thing to it is the "Game is now safe to leave" feature that kicks in when someone leaves the game. The side favoring a proper surrender option says it's better to just surrender to an assured loss and move on, while the other says the option would ruin the game's sense of competitiveness and make the potential for comebacks even worse than it currently is.
In April, Valve introduced a mute system where players above a certain report threshold lose the ability to communicate with the rest of their team. The main dev site has been embroiled in a massive flame war ever since.
Character Tiers: While there isn't exactly an "Official" tier list, there is general consensus on the quality of most heroes. Cries of anguish from teammates when they see someone pick Meepo in a pub is the most evident example of this.
It's worth noting that these can vary widely depending on the latest patch, region, skill level, and even individual games as a draft unfolds. Generally there are about 10-15 top picks at any one time, a wider roster of about 30-50 that will be picked up often but not always, 20-30 who will only be picked rarely, and at least 10-15 heroes are seen as virtually useless or inferior to other options.
Game Breaker: As balance patches come and go, sometimes what seems like a small change can hugely affect the overall prowess of heroes, especially in the competitive scene where skill levels and team compositions can magnify specific advantages. Other heroes will become popular for a month or two as they seem unstoppable, then gradually fade away again as the metagame adapts to their counters. This is standard practice for Dota, and has been the case for years.
Heroes that are consistently considered overpowered include Dark Seer (possibly the best offlaner and one of the best junglers, and a natural utility item carrier who frees up supports to ward), Io (who's mere presence in a game leaves open the possibility for ganks out of nowhere), and Batrider (who is one of the best offlaners, the best jungler, and has one of the best disables in the game, as well as a good pushing/counterpush skillset). All are considered broken, yet impossible to change without making them useless; when Batrider suffered a nerf in his porting to Dota 2, he completely fell off the map until getting buffed, whereupon he immediately became a Game Breaker again.
Most Annoying Sound: Just about anything Storm Spirit does. Imagine this going on for over an hour: "I'm over here!", "BLOOOOW THE MAN DOWN!", "Touche!", "ZAAAAAP!", "BLOW THE MAN DOWN!", "Puddin pop!", "I'm over here!" "Where's the party?" "Who's that handsome devil?" "I'm over here!" "Where's the party?" "ZAAAAAAP!" "I'm over here!" "Over here now!" "Where's the party?" "ZAAAAAAAAP!". On the other hand, Storm Spirit has quite the sizable fandom who considers his voice to be a strong contender for Most Wonderful Sound.
The same cannot be said for Windrunner, whose various quotes, including such nuggets of banality as "You hit... a girl!" "Why do you hate... gingers... so much?" "Bury me... beneath the tree..." "Ooh, now I get to shoot stuff!" and of course "Your tiny featherless arrows can't hurt me, Sniper!" have earned the ire and ridicule of many a player.
Narm / Narm Charm: Some of the heroes have really bad voice work. Luna in particular has become memetic for this gem.
Rescued from the Scrappy Heap: Alchemist used to be rarely seen in matches due to his rather bizarre skillset, an unreliable stun that can easily backfire, a crippling reliance on farming, and an ultimate that is equally reliant on farmed items. However, thanks to a few patches, he's a lot better than he used to be and is now actually a viable choice. Considering that he was basically a Joke Character before said patches, that's saying something.
Spirit Breaker received a massive buff late last year, causing him to go from barely seen in games to one of the top picks.
Naga Siren and Morphling, after being widely detested for being ubiquitous at The International 2012, suffered heavy nerfs. However, they slowly worked their way back into the meta by the time of The International 2013 where they're becoming more of a crowd pleaser.
Heaven's Halberd, a decent mid-game item with evasion and a disable, has found a niche as a lategame support item for additional bulk. Prior to this, the item was considered basically useless, and inferior to Abyssal Blade.
Sacred Cow: Comparing this game to another MOBA will get you obliterated on certain forums and imageboards.
Scrappy Mechanic: For new players; pull timing is a huge hurdle to learn once you've become more used to it. If a support improperly pulls, the lane will instead push, counteracting what you were trying to do.
Linken's Sphere can be one sometimes. Some abilities, such as line stuns (Jakiro's Ice Path, Nyx's Impale) will be blocked if targeted on the unit but work if they're ground targetted. This is a matter of no small annoyance, for both stunners and Linken's holders.
Fans of the original game often react poorly to changes. Even something as simple as names and appearances, which often need to be changed for copyright reasons names, can cause a backlash amongst veteran fans. Examples that come to mind are Brewmaster (originally known as Pandarian Brewmaster) being turned from a standard Panda to a Red Panda, Doombringer having his name changed to Doom, and Bristleback having his name (temporarily) nerfed to Bristlebog. It seems that Blizzard has their finger on the lawsuit trigger the moment Valve slips up.
Patch 6.79. Being probably the biggest patch in the game's recent history, it hugely altered the meta, much to the chagrin of the fanbase.
Averted with Storm Spirit's remodel. When it was initially announced that he would receive a new model, the playerbase assumed the worst. When it was finally revealed though, the playerbase immediately changed its tone.
Tier-Induced Scrappy: Quite a few heroes are innately unbalanced in pub games, while others require massive amounts of skill to use effectively, rarely making their appearance in pub games simply because they're very difficult to use:
Meepo is a classic case of Difficult, But Awesome; skilled Meepo players can reach the level cap and amass items long before any enemy carries come online. The problem is that if only a single Meepo dies, all of them die, and illusion based heroes like Chaos Knight and Phantom Lancer can fill a similar role without being as vulnerable.
Broodmother consistently has the lowest winrate in pubs and is almost completely ignored in pros simply because her spiderlings are free gold for anyone with AOE. Unlike other heroes with summons, Broodmother relies on summoning a lot and swarming heroes and structures with them. However, they're very low health, so they are very easy to farm.
Io is detested amongst western pro players for essentially being a necessary ban in most professional games.
Ursa is something of a one trick pony; he can apply massive physical burst but can be kited around easily with teamwork. This is rarely present in pub games.
Huskar is extremely common in low level queues but disappear above them because he's largely viewed as worthless. Huskar requires players to balance their health very carefully, and can easily be disrupted before building magic immunity by simply stunning him. He essentially rely on the enemy team underperforming, and when they stop doing so, the heroes become far less useful.
Nature's Prophet: if you ever turn your back on a tower for a minute, you can be sure that he will be applying pressure.
Spirit Breaker during the 6.78 patch is borderline-broken in pubs as his stuns are much more powerful and will go through magic immunity, and pubs rarely have the precision or teamwork to quickly respond to a caught out teammate. However, after the 6.79 nerf (Nether strike now uses cast animation along with his reduced attack speed), his win rate dramatically plummeted to manageable levels.
Vanguard as an item is generally viewed as inferior to a Mekansm. Vanguard is more effective for damage reduction, but quickly falls off in effectiveness, doesn't offer anything to a team or farm, and generally isn't worth the investment. These days, it's seen as a situational item at best for heroes with damage return passives, like Axe and Spectre.