Why look like a complete slob?
Although some will pillory dress codes for engineering grunts, there are some limits as to what is or is not acceptable dress. Dirty clothes? NO! Torn clothes? Nyet? Not even cutoff shorts. T-shirts? Not really a good idea. Shorts? OK in warm weather, else forget about them. Jeans? No problem.
An engineering grunt making a presentation to some corporate suits? Well, where I once worked in marketing, I had my several power suits and Italian dress shoes that made me look like one of them. You want instant respect from the suits? Dress like one of them. Ties that reveal your quirky personality or peccadillos are optional. Never ever had a problem dealing with corporate execs or military brass when dressed well.
But some engineers are slow learners when it comes to dress and other social graces. And these guys make enough money that they can afford to spend a few pence on clothing.