The fastest guy that I have ridden with extensively is sort of this way. Never has shaved his legs. Always wears a white t-shirt instead of a cycling jersey. Rides a 90s cannondale with downtube shifters and old helmet. (Although I heard that he finally bought a new bike now that he has moved back west).
Anyone who makes the mistake of thinking that he is anything but a fearsome presence will soon find out they are dead wrong. In his peak training years he was riding 500 miles a week and winning all the time. Sometimes I think he was just trying to fool the roadies into thinking he was just a goofball, because his M.O. was to enter long races, break away early, and never be seen again. If they don't take you seriously, then they are more likely to give you more of a gap.
His best 100 mile solo time is 3:45.