This is probably gonna be a funny question, but I am curious.
Chewing on lips?
Picking at scabs?
Seriously, though, are these bad habits sinful? I read a story of a vision of St. Don (spelling?) Bosco today and “bad habits” being sinful was mentioned. I kinda assumed it was a euphemism for solitary sexual sins, but it got me wondering. Such bad habits as are listed here are self-destructive, unhygenic, and just plain gross, some of them. But are they therefore sinful, for grown ups who should know better?