In today's Yeshiva world the dress code is dark suit, white shirt, black hat, long payists behind the ears, and probably a beard. What is fascinating is that this is a modern phenomenon. If you look at any pictures from the pre-war yeshivas (for example in הרב מבריסק, where you have pictures of various post war Rosh Yeshivas when they were young in Europe) you will see that all the unmarried guys were clean shaven with regular sideburns. In addition they were dressed stylishly in nice looking grey suits and hats. This changed for some reason in the last 40 years. So much for recreating the world of Eastern Europe.
As an aside, this whole long payists behind the ears thing is not על פי דין at all. The shiur of payists is very very short, and in fact because it is a לא תעשה there is probably not even an ענין of הידור מצוה. What is even more interesting is that someone who shaves and has long payists is being silly. There are a number of דעות in ש"וע that פאות הראש extend very far down so by shaving there they are being over an איסור דאורייתא while by growing the hair higher up long they are not מקיים anything על פי דין.
