What have Sam and Dean noticed about Vince Vincente respectively?
It really seems like Sam has noticed his music.
Dean has noticed his butt, his crotch, his leopard prints and his rainbow wig.
Also - Sam, a fan of Vince Vincente’s, doesn’t remember a rainbow wig. Which is something that kinda catches people’s attention if someone wears it. So it’s possible that Dean’s mind has constructed that memory. You know, constructing memories of rainbow wigs on men wearing spiked codpieces, as a straight man’s mind does.
I want to add a little footnote. Dean has obviously strong feelings about Vince Vincente. He is not neutral about him. Earlier, in 12x04, when Sam is like “the rockstar?” Dean replies, “The douchebag!”. He is very vocal about his disdain for Vince’s on-stage persona.
a) Dean has a thing for hot rock stars. Especially if they have a very sexually-charged on-stage persona (spiked codpiece, leopard prints, not exactly demure clothing). His crush for Vince came in a very inappropriate time of his life. He needed to be John’s perfect son, damn that stupid guy with his stupid butt and his stupid sexy guitar, right? Ugh what a douchebag with his over-the-top outfits and all…
b) Dean felt betrayed by Vince. Now this is all speculation because we don’t know Vince’s sexuality; he might have been bisexual, but all we know is that he had a female partner and possibly several female lovers. It’s possible that either he was straight, or he wasn’t publicly known as queer anyway. Either way, young Dean sees this highly queer-coded guy, but the guy is straight (for real, or in Dean’s eyes).
“Don’t judge a book by his cover.” “Or a dude by his rainbow wig and leopard prints!”. Could this be interpreted, under the surface layer of “c’mon Dean he was over-the-top in his appearance but was an okay musician!” “No way”, as, “this douchebag used to dress and act like a queer person, but apparently you can’t judge a book by his cover - it was just a stage persona and the guy was just ‘queerbaiting’!”.
Let’s compare Vince Vincente with another character that has a very similar narrative to his - Gunner Lawless. Men past their prime, once famous and beloved artists in their fields, now aging and nearly forgotten, who make a deal with a demon and the devil respectively out of loneliness and desperation… Dean idolizes Gunner even after so many years; and what do we know about Gunner? That, when faced with a smitten male fan, he flirts back.
In an episode about rock stars, Dean doesn’t mention liking rock stars. He mentions liking gladiators, outlaws and pirates. *looks into the camera*