The blog manages to make the characters likable even though they're talking about stuff like murder, rape and other such squicky things. How this works, at least in my opinion, comes down to 4 reasons:
1: With the exception of one picture, Pinkamena is hardly ever actually shown doing any of her "hobbies" (and even when she is, it's usually offscreen). Everything is implied instead of just straight up shown to you
2: Pinkamena doesn't treat the stuff she does as an obsession, but rather as little things she does in her spare time. If she were going on and on about how she is obsessed with doing all the stuff she talks about, I would imagine it would be a lot more disturbing. In a way, it's actually kind of interesting to see her treat all these horrendous things she does as no big deal
3: There are a fair bit of cute moments in the blog, and because the blog itself has a very dark, depressing, and creepy tone and subject matter, it makes the cute moments that much more cute in contrast. It just goes to show that if
Fi M can make a cannibalistic, murderous, rapist psychopathic duo incredibly cute, it can make anything cute. ANYTHING
4: It's implied that Pinkamena and Scootaloo are totally aware of the fact that what they're doing is wrong, or at least what's considered by public opinion to be wrong. They just don't really care
The art is definitely another good part of it. I like the idea of making it pink, but a really dark, faded out pink, as the idea of the blog is essentially taking a happy, vibrant character (who is also noticeably very pink) and putting a dark, depressing spin on her
I love how Scootaloo is portrayed in this blog, she possibly more likeable than she is in the actual show (since she seems to lack her bossy attitude that she has in the show) If Scootaloo wasn't in it, this blog would only be half as cute as it is, especially since most of the cute scenes come from Pinkamena and Scootaloo's interactions. I like how Scootaloo's cheerful happy personality kind of goes against Pinkamena's depressing, emo personality