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.
Accidental Aesop: For Paranormal Activity 2: Never foist your problems on your in-laws.
Alternative Character Interpretation: The demon in the first one. Despite what is revealed about it in the later installments, more than one watcher thought to themselves that they would probably kill Micah too, if they were demons and he stayed in the place they lived all day and yelled at them for moving stuff or doing anything aside from sitting quietly and never moving or making any noise.
Complete Monster: SweetGrandma Lois is revealed as the worst the series has to offer in the third entry in the series. All of the horror stemming from the demon plaguing the family can be traced back to her. It is revealed that Lois is a witch and the head of a coven that bargained with the invisible demon, in return for personal gain, to surrender the first male member of the family to the demon. To that end, Lois allows her daughter, her daughter's boyfriend and two young daughters into her home along with the demon. Lois orchestrates the death of her own daughter and watches her boyfriend's brutal death when the man tries to rescue the little girls. The film ends with Lois about to conduct a ceremony with the little girls and the demon, fully aware that eventually her great-grandson will be taken by the demon and her granddaughters' lives ruined or ended, all because of Lois’s personal greed.
Cowboy Bebop at His Computer: The Netflix description of 3 says it is a sequel instead of a prequel to the series, and that 4 takes place 5 years after 3 instead of 2.
On a similar note, in 3, when Katie is beating the hell out of a piñata at her birthday party, Dennis jokingly comments that "(Katie's) a little monster".
God-Mode Sue: The fucking cult. As the films go, there seems to be no way of stopping them and they keep growing and growing, by the the end of 4, there's around hundreds of them. This is basically the result of the faltering fanbase, getting tired of them constantly winning in every film and results with Darkness-Induced Audience Apathy.
This is a large part of what the demon does in the first film. It spends most of the film just fucking around with Katie and Micah until the last 20 minutes or so when the demon decides to go for full-blown Nightmare Fuel.
In an early jump scene, the protagonists listen carefully after Katie thinks she hears something. After a few moments of dead silence, there is what can only be described as an extended scream/howl, followed by a massive thump. Bricks were duly shat.
The sequel manages to do this with a children's toy.
An infamous scene from 2: during the day in the second movie you get about a minute of silence before everything in the kitchen flings open and falls.
Shortly after the above-mentioned kitchen scene, there's the piercingly loud whistle of the kettle.
Also from 2: Hunter's screams of terror.
Any time the demon is heard making some kind of vocal noise, like growling, roaring or breathing.
Hype Backlash: Much like The Blair Witch Project before it, getting so many reviews dubbing it one of the scariest movies of all time ensures that some people will watch it and end up unimpressed.
It's the Same, Now It Sucks: An already common criticism of Paranormal Activity 2 and the following sequels is that it too frequently uses familiar scenes from the first movie.
Jerkass Woobie: Micah; arguably Dan as well. Yes, they are unsympathetic for a lot of viewers, but eventually Micah all but abandons his Jerkass and It's All About Me attitude and shows that he really does care about Katie. In the case of Dan, while his act of transferring the demon to Katie is seen by some as a Moral Event Horizon, he does it out of his desperation to protect his wife and son. Unfortunately for him and his family, it doesn't work.
Narm: While the footage of Robbie climbing into bed with Alex is supposed to be creepy, many people found it more adorable.
The Woobie: Ali in 2. First her parents don't believe her when scary things begin to happen, one day her stepmother wakes up acting like a cross between a wolf and a serial killer. Then, oh, things are looking up! No horror for three weeks! Until you come home to find your family brutally murdered.
Any heroic dog in a horror movie is almost contractually obligated to be the most sympathetic character in the movie. Hence, Abbey. But thankfully she lived.
Dennis in the third film. He did cared for his stepdaughters and wife and wanted to find out about the demon and save his family. Yet his wife dies in front of him and is killed by his mother-in-law. All while trying to save his stepdaughters.
Kristi. The events of 2 and 3 would have been prevented had they just listened to her. Also, Dan (in the second) and Katie (in the third) are mean to her for little reason.
Katie. Imagine being haunted constantly by a demon and spending the rest of your life possessed by it, where you have killed several people including your own sister with no control. AT ALL
Alex from P4. It wasn't her fault that she and her family adopted the one boy the demon was after.