Wano was a a terrible arc for Usopp, there’s no sugarcoating it, but it was more that he was underutilized rather than that it assassinated his character. The biggest indictment on the Fanbase’s reading comprehension via-a-vis Usopp in Wano is the scene of Toko using his toad oil to try and save Yasuie. Upon re-reading the arcI’m not sure how in the world this was ever interpreted as Usopp being intentionally scummy or malicious. Here are a few quotes from users completely misunderstanding the situation.
As you can see the common interpretation of the scene is that Usopp freely choose to sell fake medicine, advertised it as a panacea, and, most egregiously, targeted the poor of Wano and specifically Tama.
The problem with this is that this is complete headcanon
. In fact it is even worse than headcanon, it is a complete fabrication made up entirely in the mind of Usopp haters.
Firstly, all jobs assigned to the strawhats in Wano were chosen by Kinemon. Usopp was only acting on information given to him by Kinemon, a native of Wano who Usopp should trust. So even if the other two points were true it would be Kinemon’s fault not Usopp’s.
Secondly, nowhere does Usopp advertise the medicine as a cure-all panacea. He only shows it healing minor cuts. How in the world could Usopp know that Toko would think it would revive a dead man.
Lastly, We know Usopp didn’t sell the Toad Oil to the starving and impoverished citizens of Wano like the residents of Ebisu town. He only sold the toad oil to the citizens of the Flower Capital, the abode of the Rich and Middle Class in Wano filled with Orochi sympathizers. Toko only got the oil, firstly, because she was allowed in the Flower Capital due to being a part of Hiuori’s entourage, and secondly, because SHE STOLE IT FROM USOPP. That’s right, Usopp never sold Toko a thing yet he still gets slander.
It’s honestly so ridiculous, imagine if any other character was slandered for something like this. Do the fans expect Usopp to have foreknowledge that a resident of Ebisu town would happen to be in the crowd because of her connections to Komurasaki, That she would steal the medicine, Yasuie’s execution, Toko’s relation to him, that she would misunderstand him, etc. The only way that this would be a valid critique of Usopp’s character is if you believe he has future sight.
Usopp later doesn't even apologize to Toko personally after he tricked her with toad oil I'm having war flashbacks 
The problem with this is that this is complete headcanon
. In fact it is even worse than headcanon, it is a complete fabrication made up entirely in the mind of Usopp haters.Firstly, all jobs assigned to the strawhats in Wano were chosen by Kinemon. Usopp was only acting on information given to him by Kinemon, a native of Wano who Usopp should trust. So even if the other two points were true it would be Kinemon’s fault not Usopp’s.
Secondly, nowhere does Usopp advertise the medicine as a cure-all panacea. He only shows it healing minor cuts. How in the world could Usopp know that Toko would think it would revive a dead man.
Lastly, We know Usopp didn’t sell the Toad Oil to the starving and impoverished citizens of Wano like the residents of Ebisu town. He only sold the toad oil to the citizens of the Flower Capital, the abode of the Rich and Middle Class in Wano filled with Orochi sympathizers. Toko only got the oil, firstly, because she was allowed in the Flower Capital due to being a part of Hiuori’s entourage, and secondly, because SHE STOLE IT FROM USOPP. That’s right, Usopp never sold Toko a thing yet he still gets slander.
It’s honestly so ridiculous, imagine if any other character was slandered for something like this. Do the fans expect Usopp to have foreknowledge that a resident of Ebisu town would happen to be in the crowd because of her connections to Komurasaki, That she would steal the medicine, Yasuie’s execution, Toko’s relation to him, that she would misunderstand him, etc. The only way that this would be a valid critique of Usopp’s character is if you believe he has future sight.
