A bochur chewing gum? Major attitude. Will most likely go hand in hand with wearing his shirt untucked, and sunglasses. (the shades are so you cannot see the pain in their eyes)
They may also be from “the best yeshiva / best family” ect, but scratch the surface, and you find not a kid at risk. You’ll find a kid who is waste deep in all sorts of troubling behavior. Think cholent (or Walmart, depending on the season) at 2:00am
Gum chewing may or not be a tnzius issue, but it sure is a red flag.