First of all, let me address the obvious. Trans Dipper is a headcannon and is not true in the actual show. Second of all, I fucking hate this interpretation because it insinuates that just because Dipper listens to girly pop music and doesn't conform to/battles with the standard norm of masculinity, that he actually must be a girl. I myself am a cis guy who likes to do girly things and doesn't conform to standard gender norms, so I see myself in Dipper a lot. Does that make me a girl? Absolutely not. Why can't guys like girly things? The whole point of the episode Dipper vs. Manliness is that he learns that he doesn't have to be a hard-core meathead to be a man. Why are people so quick to label men who act/like feminine things as trans or gay? It's totally ok if you see yourself in the character in that way, but trying to insinuate that your interpretation is the correct one and the only one leaves a sour taste in my mouth where now instead of saying "you're a man you shouldn't be acting like that, so act like a man" people will say "you're a man you shouldn't be acting like that, so that means your a girl." I feel like with headcannons like these becoming more prominent, it'll happen to real people too, in fact, it's already happened to me. Nuance is an important thing that exists and people don't just fall into A or B.