Originally Posted by Newton
Never wear a polo with a suit. Fullstop.
Never ever buy a black double-breasted suit from a thrift shop. Or borrow one from your Dad
It looks horrible and cheap.
I dont think there's anything inherently wrong with wearing a polo shirt with a suit. I admit it's far mor right after hours than it is "on the clock" But there are some industries where it pays to dress this way and it is detrimental to wear a tie, I mean if you want to get on. I admit that a washed out cheap polo shirt is a bad choice and an expensively made (good construction, hand finishing) one in a high count cotton, merino wool or even cashmere is a better choice. Make sure the collar is large and substantial enough to stay under your jacket collar.
Additionally, this is a look with a tradition, it isnt "just" contemporary.
This might be of interest to you:http://www.filmnoirbuff.com/article/...-casual-attire
And as texas-jack said, what if the DB black suit is custom or from a sumptuous ready to wear manufacturer?