90% of the time, it's that they are wearing off the rack clothing that's a normal fit. The sleeve doesn't break at the shoulder line because it's draping off of them, sweaters are baggy, they look like they are swimming in dress shirts. Most of these guys have no idea about their jacket size, don't know where seams are supposed to fall, and probably still aren't wearing the right sized pants. Poor fit has most everything to do with it.
On top of that, most men in their early 20's-30's feel like they have to have a statement item or try to dress things down with a pair of sneakers or something. I sit in meetings all day with guys that wear dress pants, long sleeve shirts, and then a pair of Jordan's and that makes them look like clowns. Nothing wrong with just going clean and classic with a well fitting suit.