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.
Its sequels have mitigated this somewhat. After Resident Evil 5 and Resident Evil 6, it's hard not to look back on 4 as the most subtle and haunting of the "new age" Resident Evil games.
What's better, the Red9 or Blacktail? Arguments over this rage to this very day.
Big Lipped Alligator Moment: There's a giant clockwork mechanical statue of Salazar in one of the castle chapters. Never explained or mentioned ever again. We can buy that Salazar has a big enough ego to build a statue of himself, but why build a giant clockwork statue that chases after people?? His ego is just that big.
The guy that bursts out of the furnace on fire could qualify as this too. What the hell WAS he doing in there?
Critical Research Failure: When they were called out on the use of the Spexico trope, the developers defended themselves by saying the game doesn't take place in Spain, but in Central Europe. Looks like nobody told them Spain is the only country in the whole continent where Spanish is spoken and the "pesetas" were Spain's currency before the Euro...
Damsel Scrappy: Ashley Graham. You'll hear "LEON HAAALLLP" so much that you're bound to want to kill her yourself by the end of the game.
Ramon Salazar to an extent as well. He certainly delights in causing trouble for Leon and Ashley and steals every scene that he's in.
That dog you save from the trap at the beginning of the game. The Video Game Caring Potential is nice, but what cements him into the hearts of fans everywhere is when he repays the favor by helping you kill your first El Gigante. Capcom has made another game called Haunting Ground where an identical dog called Hewie spends most of the game as the protagonist's loyal companion.
Epileptic Trees: There's a lot of WMGs regarding the identity of the Merchant.
Failure Hero: Averted in the end. Despite his skills Leon sometimes makes bad decision like trying beat the Big Cheese in hand to hand combat or failing to protect Ashley from giant flys. If it weren't for Ada's assistance Leon might have failed several times and even died.
The suit of armor that you can equip Ashley with makes her completely invulnerable, even from enemies that try to kidnap her.
What makes this even worse is that you can switch costumes on your first Professional Mode playthrough... Meaning that you can play through the entirety of Professional Mode without having to worry about Ashley's safety.
The P.R.L 42 can kill Mendez, the Garradors, living armor, Verdugo, U-3, Krauser and even Saddler in no more than two stun flashes. Utilizing both of these features a player could complete everything in the game using nothing more than the base handgun, one box of ammo, three grenades and a handful of healing items.
Goddamned Bats: The Novistadors are not well-liked among the Resident Evil community. At least they kidnap Ashley so you don't have to look after her...
For those who don't get creeped as easily, the monks' chanting referenced up in Hell Is That Noise can become this instead.
Most Wonderful Sound: The soft clarinet music you hear in some saving rooms is very relaxing, especially when you just went through a hellish survival sequence. This is pretty much tells you "Don't worry, it's safe here."
Rescued from the Scrappy Heap: The knife was the most useless weapon in the series (save for showoff gamers). This game turns it into one of the most useful weapons, including making it the best way to take out Krauser.
That One Level: The very first level, where all you have is the basic pistol, a knife, and maybe a couple of grenades. After facing about 6 enemies in groups of at most two, you come to the village where you can end up with about a dozen villagers, two with chainsaws, coming after you.
The "Ball Room" in late game. There's little space to maneuver, Elite Mooks are coming at you from every direction, who have the highest Plagas spawning chance in the game and will constantly get reinforcements until you've taken down a substantial amount of them, and you have to protect Ashley during the whole process. Prepare to hear "LEEEEEEEOOOON!! HAAAAAALP!!" a lot.
Mike the helicopter pilot. How many times in this series can you say you have a chain gun and missile launcher-toting helicopter coming to your aid, and doing a damn good job at that? It's nothing short of a travesty that he and Leon weren't able to stop by that bar he mentioned.
Uncanny Valley: Ganadoes seem human at a distance, but as you get closer their red eyes and odd movements push them into the valley.