At milongas we see people wearing many different types of clothes. The ladies are nearly always immaculately turned-out. They have clearly spent time & effort & money to look great, and it works. One of the joys of milongas for me is to dance with lovely ladies who look good.
As for the men… I don’t care how good a dancer you are, I believe that the clothes you choose to wear show your respect to the ladies. I choose to look smart, and I’ve found that this also affects the way that I dance; I walk taller and feel good beside my beautiful partner.
Some tango leaders try to look cool by wearing casual street clothes to dance. Mistake. I think it looks just plain scruffy. So please resist the “urban cool dude” look: dirty, ragged cargo pants, old T shirt, trainers, stubble, etc etc. Scruffy clothes are disrespectful to the followers. End of.