As I write this I am in a Nike Tshirt and blue jean shorts. I am not wearing shoes. I am at work. It is lunchtime so relax. I work in an office by myself when I am not traveling, so sometimes I do not even shave.
When I visit customers I wear a suit and tie. I wear black wingtip shoes that tie. I keep them polished, even the edges of the sole. I wear a white dress shirt 99% of the time. On very rare occasions I will wear a blazer and slacks.
Few in my profession dress this way anymore when visiting customers. Most wear a logo golf or polo type shirt and Dockers. Unless I am going to play golf with a customer I cannot bring myself to do it. I represent my company, and they deserve my best. Hey, I am not a good looking guy (see my picture if you do not believe me), at least I can dress nice.
Frankly, it has now become a matter of pride and pigheadedness. I may not be the best salesman, or the brightest bulb to call upon an equipment manufacturer, but they will remember me. When quality is a given, delivery is essential, and we cannot beat the Chinese on price, it is my personality that closes the deal. Look professional, act professional and the customer will know they are doing business with a serious vendor, not a golfing buddy.
Hey, I am so lousy at golf that is all I have!