Now for girls I suppose no underwear would be considerably worse then guys. Me, being a guy and only wearing boxer shorts anyway, just never though about it guess I will try next time as my boxers were kinda bunching. ;-)
Now a funny story:
My girlfriend wears proper cycling attire and sometimes covers it with other clothes depending on weather/where we are.
That said, the other day I was heading down the parkway and this guy and his gf were coming up on some low end bike store bikes (just a shot above dept. store bikes) and as she is coming up she tries to pull up her ultra low rise jeans, im like hmm and as she goes past my friend notices her pink thong is still sticking way out. How ditzy can you be to ride in ultra-low jeans with a thong on. Do some people have no common sense.