The 26-year-old internet superstar and pugilist was spotted on camera touching his nose as he stood behind his older bro following his win over Dillon Danis in Manchester ... with many going to social media to accuse him of sniffing the booger sugar in plain sight.

Paul addressed it all in his most recent YouTube video ... poking fun at the wild claims by surrounding himself with Coca-Cola cans and tossing a white powder in the air like LeBron James.

"Y'all want some Coke?" Paul asked his friends as he pretended to be drugged out.

After laughing it off, Paul got serious ... saying his gesture was the result of being a sweaty guy -- even zooming in on his nose to show how moist his skin gets from "five minutes of existing."

On top of that, his involvement in the post-fight scuffle certainly didn't help his perspiration problem.

"This is the thing, is I go to brawl in the ring to save my f***ing brother," Paul added. "Forty grown men around me, everyone's huffing and puffing, I'm yelling, 'You bitch, you're lucky I didn't kill you.' and I'm literally drenched in sweat."

"I come out, everyone knows I'm the most sweatiest person in the world. So I get into the ring to like, go be there for my brother and s***, and I put my hat on and I'm literally sweating down my face, so I'm just like this, trying to get the sweat off of my f***ing face."

Paul's girlfriend, Jutta Leerdam, backed her man ... saying she's seen first-hand how seriously he takes care of his body -- and all the haters need to quit trying to create a false image of him.