In chapter 28, the reader is set up to think that Cecil is back to scare them again. However, it's not Cecil. Jem hears something moving when they move. Scout assumes that it's Cecil and blurts out his name and calls him a "big fat hen."
Then as they made their way, their "company shuffled and dragged his feet, as if wearing heavy shoes. Whoever it was wore thick cotton pants; what I thought were trees rustling was the soft swish of cotton on cotton, wheek, wheek, with every step."
From chapter 29, we see Boo in a similar light that was described by the children in chapter 1. Other than the drooling and the jagged scar across his face, he did look like he'd never seen the light of day. "His face was as white as his hands...his cheeks were thin to hollowness...and his gray eyes were so colorless I thought he was blind. His hair was dead and thin, almost feathery on top of his head." Boo was not scary to look at. However, he was scared of them, as he hid in the shadows throughout the end of the book.