Youths - not pejorative. For example, many of the services for young people are referred to as 'youth' services. If I wanted to identify a lad (not a girl) who was neither a boy nor a man, I might refer to him as a youth.
Yoofs is different to 'youth'. Yes, I used it to suggest 'up to no good' but in a very minor, light-hearted way. Hanging around, doing nothing useful in a way that would make and mother in (early) middle-age like me wag my finger. Not suggest criminal or disruptive behaviour. I chose it deliberately and put it in inverted commas because, as mentioned, it was really coined by the media and refers to a social group rather than anything sinister.
Never, ever have I thought it referred to any one ethnic group, or excluded any.