Sins of the Fathers Chapter 6: Framed - S3-E6
Plot hole: After Peter Parker is framed and arrested for selling government secrets to foreign organizations, he escapes police custody and goes home to retrieve his Spider-Man costume that was simply hanging in his dark room. If he was arrested for selling government secrets then surely the police would have searched his home and found his costume (as well as equipment) in the process. Since the police car was visible in front of his house, it seems very strange that police didn't search his home.
Sins of the Fathers Chapter 7: The Man Without Fear - S3-E7
Plot hole: They forgot Daredevil can sense when someone's lying, one of his powers. So, he should've known Spider-Man was telling him the truth about the computer disk.
Answer: I believe it was just a way to try and show the suit is "oily" or reflective. It also helps define the character's features since otherwise, he'd just be a flat black color. It's similar to how the black suit Spidey had blue outlines. (I don't know why they chose a pink/red color... maybe because red is associated with power/fire/war, so it's a more "evil" color?)
TedStixon