Hoodies are a symbol ...
... of an underworld or criminal figure with a need to conceal their identity. Odd, because any hacker worth their salt won't place themselves in a position where surveillance has any effect.
Hoodies, or wool caps and parkas worn on 85°F days are a symbol of an individual who is frail*. So frail that they don't have a metabolism capable of maintaining proper body temperature under the mildest of conditions. Sort of the opposite of the above 'bad boy' image.
*There is a school of thought that heavy pot use can adversely affect body temperature regulation. It' always seems to be the stoners that bundle up on even the warmer days.