Why am I not very good? Why aren't you talking about his alignment?
I think he's town. As for why I don't think you're very good - if I accept your play as being genuine and not motivated by trolling (which I'm not sure I actually do concede, but for arguments sake I'll assume good faith), then you struggle with handling suspicion on players. You pick on small amd insignificant details that aren't very persuasive or indicative of anything, and frame them as alignment-determining. And worse, when presented with arguments contrary to your position, you fail to ever demonstrate the ability to reflect on your positions. You get too tunnelled, and then soend your time framing everything that player does as scummy, whether it is or isn't. This not only hurts the credibility of your arguments, because it's not very persuasive when it's made clear that there isn't a consistent logic underpinning your thoughts, but rather a conclusion that's driving all of your opinions, but it also means that when you're wrong, there is never any way for you to course correct.
After that, there are other reasons - you lie about claims and come up with shaky and flimsy justifications for doing so, and haven't demonstrated the level of insight required for knowing when to lie as town. And the way you handle your suspicions causes players, and not just the targets of your suspicion, to not want to engage with you or even read your posts, which limits how effective your posting can be for the town to the point where it's almost entirely disregarded out of hand. It promotes negative health for the thread which instantly tanks your value as town too. It also means you have a high rate of being mislynched and killed as town, which in turn hurts your ability to play as scum.
That's the most polite way I can describe it.