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.
Alternate Character Interpretation: Avril is a vampire. Specifically, the stranger from "I'm With You" turned her and Under My Skin was inspired by someone that she accidentally killed. "Here's To Never Growing Up" is her vampire anthem.
Her reasons for breaking up with Deryck Whibley. Many people feel she had a right to move on, while others aren't too happy, mainly because many believed Avril helped Deryck stay sober. It's rather uncomfortable considering that Deryck's ended up suffering from kidney failure.
Fridge Horror: In the "Girlfriend" music video, the nerdy girl gets hit in the head with a golfball and falls in a decorative river. Those things are notorious for being bacteria-riddled, so one hopes she didn't get any in her mouth. And, later, she's still stumbling around, which means she probably has a concussion.
Harsher in Hindsight: The video for Nobody's Home featured a homeless version of Avril and a shallow/spoiled version of Avril. Her default look in recent years looks basically exactly like the shallow version of her from that video.
"Hello Kitty" has incited several flame wars. Aside from debates over its quality and whether the music video is offensive or not, the Dubstep elements don't help it either. Fans of the genre call it a cheap knock-off song created to cash in on dubstep having become a mainstream thing, non-fans just hate it due to their pre-existing dislike of the genre, and others find it to be fitting for the song.